diff --git a/contrib/subtree/git-subtree.sh b/contrib/subtree/git-subtree.sh
index 308b777b0a..edf36f8c36 100755
--- a/contrib/subtree/git-subtree.sh
+++ b/contrib/subtree/git-subtree.sh
@@ -90,7 +90,7 @@ while [ $# -gt 0 ]; do
 		--annotate) annotate="$1"; shift ;;
 		--no-annotate) annotate= ;;
 		-b) branch="$1"; shift ;;
-		-P) prefix="$1"; shift ;;
+		-P) prefix="${1%/}"; shift ;;
 		-m) message="$1"; shift ;;
 		--no-prefix) prefix= ;;
 		--onto) onto="$1"; shift ;;
diff --git a/contrib/subtree/t/Makefile b/contrib/subtree/t/Makefile
index c864810389..276898eb6b 100644
--- a/contrib/subtree/t/Makefile
+++ b/contrib/subtree/t/Makefile
@@ -13,11 +13,23 @@ TAR ?= $(TAR)
 RM ?= rm -f
 PROVE ?= prove
 DEFAULT_TEST_TARGET ?= test
+TEST_LINT ?= test-lint
+
+ifdef TEST_OUTPUT_DIRECTORY
+TEST_RESULTS_DIRECTORY = $(TEST_OUTPUT_DIRECTORY)/test-results
+else
+TEST_RESULTS_DIRECTORY = ../../../t/test-results
+endif
 
 # Shell quote;
 SHELL_PATH_SQ = $(subst ','\'',$(SHELL_PATH))
+PERL_PATH_SQ = $(subst ','\'',$(PERL_PATH))
+TEST_RESULTS_DIRECTORY_SQ = $(subst ','\'',$(TEST_RESULTS_DIRECTORY))
 
-T = $(wildcard t[0-9][0-9][0-9][0-9]-*.sh)
+T = $(sort $(wildcard t[0-9][0-9][0-9][0-9]-*.sh))
+TSVN = $(sort $(wildcard t91[0-9][0-9]-*.sh))
+TGITWEB = $(sort $(wildcard t95[0-9][0-9]-*.sh))
+THELPERS = $(sort $(filter-out $(T),$(wildcard *.sh)))
 
 all: $(DEFAULT_TEST_TARGET)
 
@@ -26,20 +38,22 @@ test: pre-clean $(TEST_LINT)
 
 prove: pre-clean $(TEST_LINT)
 	@echo "*** prove ***"; GIT_CONFIG=.git/config $(PROVE) --exec '$(SHELL_PATH_SQ)' $(GIT_PROVE_OPTS) $(T) :: $(GIT_TEST_OPTS)
-	$(MAKE) clean
+	$(MAKE) clean-except-prove-cache
 
 $(T):
 	@echo "*** $@ ***"; GIT_CONFIG=.git/config '$(SHELL_PATH_SQ)' $@ $(GIT_TEST_OPTS)
 
 pre-clean:
-	$(RM) -r test-results
+	$(RM) -r '$(TEST_RESULTS_DIRECTORY_SQ)'
 
-clean:
-	$(RM) -r 'trash directory'.* test-results
+clean-except-prove-cache:
+	$(RM) -r 'trash directory'.* '$(TEST_RESULTS_DIRECTORY_SQ)'
 	$(RM) -r valgrind/bin
+
+clean: clean-except-prove-cache
 	$(RM) .prove
 
-test-lint: test-lint-duplicates test-lint-executable
+test-lint: test-lint-duplicates test-lint-executable test-lint-shell-syntax
 
 test-lint-duplicates:
 	@dups=`echo $(T) | tr ' ' '\n' | sed 's/-.*//' | sort | uniq -d` && \
@@ -51,12 +65,15 @@ test-lint-executable:
 		test -z "$$bad" || { \
 		echo >&2 "non-executable tests:" $$bad; exit 1; }
 
+test-lint-shell-syntax:
+	@'$(PERL_PATH_SQ)' ../../../t/check-non-portable-shell.pl $(T) $(THELPERS)
+
 aggregate-results-and-cleanup: $(T)
 	$(MAKE) aggregate-results
 	$(MAKE) clean
 
 aggregate-results:
-	for f in ../../../t/test-results/t*-*.counts; do \
+	for f in '$(TEST_RESULTS_DIRECTORY_SQ)'/t*-*.counts; do \
 		echo "$$f"; \
 	done | '$(SHELL_PATH_SQ)' ../../../t/aggregate-results.sh
 
diff --git a/contrib/subtree/t/t7900-subtree.sh b/contrib/subtree/t/t7900-subtree.sh
index dfbe443dea..751aee3a0c 100755
--- a/contrib/subtree/t/t7900-subtree.sh
+++ b/contrib/subtree/t/t7900-subtree.sh
@@ -5,7 +5,7 @@
 #
 test_description='Basic porcelain support for subtrees
 
-This test verifies the basic operation of the merge, pull, add
+This test verifies the basic operation of the add, pull, merge
 and split subcommands of git subtree.
 '
 
@@ -14,13 +14,21 @@ export TEST_DIRECTORY
 
 . ../../../t/test-lib.sh
 
+subtree_test_create_repo()
+{
+	test_create_repo "$1"
+	(
+		cd $1
+		git config log.date relative
+	)
+}
+
 create()
 {
 	echo "$1" >"$1"
 	git add "$1"
 }
 
-
 check_equal()
 {
 	test_debug 'echo'
@@ -38,408 +46,15 @@ undo()
 	git reset --hard HEAD~
 }
 
-last_commit_message()
-{
-	git log --pretty=format:%s -1
-}
-
-test_expect_success 'init subproj' '
-	test_create_repo "sub proj"
-'
-
-# To the subproject!
-cd ./"sub proj"
-
-test_expect_success 'add sub1' '
-	create sub1 &&
-	git commit -m "sub1" &&
-	git branch sub1 &&
-	git branch -m master subproj
-'
-
-# Save this hash for testing later.
-
-subdir_hash=$(git rev-parse HEAD)
-
-test_expect_success 'add sub2' '
-	create sub2 &&
-	git commit -m "sub2" &&
-	git branch sub2
-'
-
-test_expect_success 'add sub3' '
-	create sub3 &&
-	git commit -m "sub3" &&
-	git branch sub3
-'
-
-# Back to mainline
-cd ..
-
-test_expect_success 'enable log.date=relative to catch errors' '
-	git config log.date relative
-'
-
-test_expect_success 'add main4' '
-	create main4 &&
-	git commit -m "main4" &&
-	git branch -m master mainline &&
-	git branch subdir
-'
-
-test_expect_success 'fetch subproj history' '
-	git fetch ./"sub proj" sub1 &&
-	git branch sub1 FETCH_HEAD
-'
-
-test_expect_success 'no subtree exists in main tree' '
-	test_must_fail git subtree merge --prefix="sub dir" sub1
-'
-
-test_expect_success 'no pull from non-existant subtree' '
-	test_must_fail git subtree pull --prefix="sub dir" ./"sub proj" sub1
-'
-
-test_expect_success 'check if --message works for add' '
-	git subtree add --prefix="sub dir" --message="Added subproject" sub1 &&
-	check_equal ''"$(last_commit_message)"'' "Added subproject" &&
-	undo
-'
-
-test_expect_success 'check if --message works as -m and --prefix as -P' '
-	git subtree add -P "sub dir" -m "Added subproject using git subtree" sub1 &&
-	check_equal ''"$(last_commit_message)"'' "Added subproject using git subtree" &&
-	undo
-'
-
-test_expect_success 'check if --message works with squash too' '
-	git subtree add -P "sub dir" -m "Added subproject with squash" --squash sub1 &&
-	check_equal ''"$(last_commit_message)"'' "Added subproject with squash" &&
-	undo
-'
-
-test_expect_success 'add subproj to mainline' '
-	git subtree add --prefix="sub dir"/ FETCH_HEAD &&
-	check_equal ''"$(last_commit_message)"'' "Add '"'sub dir/'"' from commit '"'"'''"$(git rev-parse sub1)"'''"'"'"
-'
-
-# this shouldn't actually do anything, since FETCH_HEAD is already a parent
-test_expect_success 'merge fetched subproj' '
-	git merge -m "merge -s -ours" -s ours FETCH_HEAD
-'
-
-test_expect_success 'add main-sub5' '
-	create "sub dir/main-sub5" &&
-	git commit -m "main-sub5"
-'
-
-test_expect_success 'add main6' '
-	create main6 &&
-	git commit -m "main6 boring"
-'
-
-test_expect_success 'add main-sub7' '
-	create "sub dir/main-sub7" &&
-	git commit -m "main-sub7"
-'
-
-test_expect_success 'fetch new subproj history' '
-	git fetch ./"sub proj" sub2 &&
-	git branch sub2 FETCH_HEAD
-'
-
-test_expect_success 'check if --message works for merge' '
-	git subtree merge --prefix="sub dir" -m "Merged changes from subproject" sub2 &&
-	check_equal ''"$(last_commit_message)"'' "Merged changes from subproject" &&
-	undo
-'
-
-test_expect_success 'check if --message for merge works with squash too' '
-	git subtree merge --prefix "sub dir" -m "Merged changes from subproject using squash" --squash sub2 &&
-	check_equal ''"$(last_commit_message)"'' "Merged changes from subproject using squash" &&
-	undo
-'
-
-test_expect_success 'merge new subproj history into subdir' '
-	git subtree merge --prefix="sub dir" FETCH_HEAD &&
-	git branch pre-split &&
-	check_equal ''"$(last_commit_message)"'' "Merge commit '"'"'"$(git rev-parse sub2)"'"'"' into mainline" &&
-	undo
-'
-
-test_expect_success 'Check that prefix argument is required for split' '
-	echo "You must provide the --prefix option." > expected &&
-	test_must_fail git subtree split > actual 2>&1 &&
-	test_debug "printf '"'"'expected: '"'"'" &&
-	test_debug "cat expected" &&
-	test_debug "printf '"'"'actual: '"'"'" &&
-	test_debug "cat actual" &&
-	test_cmp expected actual &&
-	rm -f expected actual
-'
-
-test_expect_success 'Check that the <prefix> exists for a split' '
-	echo "'"'"'non-existent-directory'"'"'" does not exist\; use "'"'"'git subtree add'"'"'" > expected &&
-	test_must_fail git subtree split --prefix=non-existent-directory > actual 2>&1 &&
-	test_debug "printf '"'"'expected: '"'"'" &&
-	test_debug "cat expected" &&
-	test_debug "printf '"'"'actual: '"'"'" &&
-	test_debug "cat actual" &&
-	test_cmp expected actual
-#	rm -f expected actual
-'
-
-test_expect_success 'check if --message works for split+rejoin' '
-	spl1=''"$(git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --message "Split & rejoin" --rejoin)"'' &&
-	git branch spl1 "$spl1" &&
-	check_equal ''"$(last_commit_message)"'' "Split & rejoin" &&
-	undo
-'
-
-test_expect_success 'check split with --branch' '
-	spl1=$(git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --message "Split & rejoin" --rejoin) &&
-	undo &&
-	git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --branch splitbr1 &&
-	check_equal ''"$(git rev-parse splitbr1)"'' "$spl1"
-'
-
-test_expect_success 'check hash of split' '
-	spl1=$(git subtree split --prefix "sub dir") &&
-	git subtree split --prefix "sub dir" --branch splitbr1test &&
-	check_equal ''"$(git rev-parse splitbr1test)"'' "$spl1" &&
-	new_hash=$(git rev-parse splitbr1test~2) &&
-	check_equal ''"$new_hash"'' "$subdir_hash"
-'
-
-test_expect_success 'check split with --branch for an existing branch' '
-	spl1=''"$(git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --message "Split & rejoin" --rejoin)"'' &&
-	undo &&
-	git branch splitbr2 sub1 &&
-	git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --branch splitbr2 &&
-	check_equal ''"$(git rev-parse splitbr2)"'' "$spl1"
-'
-
-test_expect_success 'check split with --branch for an incompatible branch' '
-	test_must_fail git subtree split --prefix "sub dir" --onto FETCH_HEAD --branch subdir
-'
-
-test_expect_success 'check split+rejoin' '
-	spl1=''"$(git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --message "Split & rejoin" --rejoin)"'' &&
-	undo &&
-	git subtree split --annotate='"'*'"' --prefix "sub dir" --onto FETCH_HEAD --rejoin &&
-	check_equal ''"$(last_commit_message)"'' "Split '"'"'sub dir/'"'"' into commit '"'"'"$spl1"'"'"'"
-'
-
-test_expect_success 'add main-sub8' '
-	create "sub dir/main-sub8" &&
-	git commit -m "main-sub8"
-'
-
-# To the subproject!
-cd ./"sub proj"
-
-test_expect_success 'merge split into subproj' '
-	git fetch .. spl1 &&
-	git branch spl1 FETCH_HEAD &&
-	git merge FETCH_HEAD
-'
-
-test_expect_success 'add sub9' '
-	create sub9 &&
-	git commit -m "sub9"
-'
-
-# Back to mainline
-cd ..
-
-test_expect_success 'split for sub8' '
-	split2=''"$(git subtree split --annotate='"'*'"' --prefix "sub dir/" --rejoin)"'' &&
-	git branch split2 "$split2"
-'
-
-test_expect_success 'add main-sub10' '
-	create "sub dir/main-sub10" &&
-	git commit -m "main-sub10"
-'
-
-test_expect_success 'split for sub10' '
-	spl3=''"$(git subtree split --annotate='"'*'"' --prefix "sub dir" --rejoin)"'' &&
-	git branch spl3 "$spl3"
-'
-
-# To the subproject!
-cd ./"sub proj"
-
-test_expect_success 'merge split into subproj' '
-	git fetch .. spl3 &&
-	git branch spl3 FETCH_HEAD &&
-	git merge FETCH_HEAD &&
-	git branch subproj-merge-spl3
-'
-
-chkm="main4
-main6"
-chkms="main-sub10
-main-sub5
-main-sub7
-main-sub8"
-chkms_sub=$(cat <<TXT | sed 's,^,sub dir/,'
-$chkms
-TXT
-)
-chks="sub1
-sub2
-sub3
-sub9"
-chks_sub=$(cat <<TXT | sed 's,^,sub dir/,'
-$chks
-TXT
-)
-
-test_expect_success 'make sure exactly the right set of files ends up in the subproj' '
-	subfiles="$(git ls-files)" &&
-	check_equal "$subfiles" "$chkms
-$chks"
-'
-test_expect_success 'make sure the subproj history *only* contains commits that affect the subdir' '
-	allchanges=''"$(git log --name-only --pretty=format:'"''"' | sort | sed "/^$/d")"'' &&
-	check_equal "$allchanges" "$chkms
-$chks"
-'
-
-# Back to mainline
-cd ..
-
-test_expect_success 'pull from subproj' '
-	git fetch ./"sub proj" subproj-merge-spl3 &&
-	git branch subproj-merge-spl3 FETCH_HEAD &&
-	git subtree pull --prefix="sub dir" ./"sub proj" subproj-merge-spl3
-'
-
-test_expect_success 'make sure exactly the right set of files ends up in the mainline' '
-	mainfiles=$(git ls-files) &&
-	check_equal "$mainfiles" "$chkm
-$chkms_sub
-$chks_sub"
-'
-
-test_expect_success 'make sure each filename changed exactly once in the entire history' '
-	# main-sub?? and /subdir/main-sub?? both change, because those are the
-	# changes that were split into their own history.  And subdir/sub?? never
-	# change, since they were *only* changed in the subtree branch.
-	allchanges=''"$(git log --name-only --pretty=format:'"''"' | sort | sed "/^$/d")"'' &&
-	check_equal "$allchanges" ''"$(cat <<TXT | sort
-$chkms
-$chkm
-$chks
-$chkms_sub
-TXT
-)"''
-'
-
-test_expect_success 'make sure the --rejoin commits never make it into subproj' '
-	check_equal ''"$(git log --pretty=format:'"'%s'"' HEAD^2 | grep -i split)"'' ""
-'
-
-test_expect_success 'make sure no "git subtree" tagged commits make it into subproj' '
-	# They are meaningless to subproj since one side of the merge refers to the mainline
-	check_equal ''"$(git log --pretty=format:'"'%s%n%b'"' HEAD^2 | grep "git-subtree.*:")"'' ""
-'
-
-# prepare second pair of repositories
-mkdir test2
-cd test2
-
-test_expect_success 'init main' '
-	test_create_repo main
-'
-
-cd main
-
-test_expect_success 'add main1' '
-	create main1 &&
-	git commit -m "main1"
-'
-
-cd ..
-
-test_expect_success 'init sub' '
-	test_create_repo sub
-'
-
-cd sub
-
-test_expect_success 'add sub2' '
-	create sub2 &&
-	git commit -m "sub2"
-'
-
-cd ../main
-
-# check if split can find proper base without --onto
-
-test_expect_success 'add sub as subdir in main' '
-	git fetch ../sub master &&
-	git branch sub2 FETCH_HEAD &&
-	git subtree add --prefix "sub dir" sub2
-'
-
-cd ../sub
-
-test_expect_success 'add sub3' '
-	create sub3 &&
-	git commit -m "sub3"
-'
-
-cd ../main
-
-test_expect_success 'merge from sub' '
-	git fetch ../sub master &&
-	git branch sub3 FETCH_HEAD &&
-	git subtree merge --prefix "sub dir" sub3
-'
-
-test_expect_success 'add main-sub4' '
-	create "sub dir/main-sub4" &&
-	git commit -m "main-sub4"
-'
-
-test_expect_success 'split for main-sub4 without --onto' '
-	git subtree split --prefix "sub dir" --branch mainsub4
-'
-
-# at this point, the new commit parent should be sub3 if it is not,
-# something went wrong (the "newparent" of "master~" commit should
-# have been sub3, but it was not, because its cache was not set to
-# itself)
-
-test_expect_success 'check that the commit parent is sub3' '
-	check_equal ''"$(git log --pretty=format:%P -1 mainsub4)"'' ''"$(git rev-parse sub3)"''
-'
-
-test_expect_success 'add main-sub5' '
-	mkdir subdir2 &&
-	create subdir2/main-sub5 &&
-	git commit -m "main-sub5"
-'
-
-test_expect_success 'split for main-sub5 without --onto' '
-	# also test that we still can split out an entirely new subtree
-	# if the parent of the first commit in the tree is not empty,
-	# then the new subtree has accidentally been attached to something
-	git subtree split --prefix subdir2 --branch mainsub5 &&
-	check_equal ''"$(git log --pretty=format:%P -1 mainsub5)"'' ""
-'
-
-# make sure no patch changes more than one file.  The original set of commits
-# changed only one file each.  A multi-file change would imply that we pruned
-# commits too aggressively.
-joincommits()
+# Make sure no patch changes more than one file.
+# The original set of commits changed only one file each.
+# A multi-file change would imply that we pruned commits
+# too aggressively.
+join_commits()
 {
 	commit=
 	all=
 	while read x y; do
-		#echo "{$x}" >&2
 		if [ -z "$x" ]; then
 			continue
 		elif [ "$x" = "commit:" ]; then
@@ -455,67 +70,948 @@ joincommits()
 	echo "$commit $all"
 }
 
+test_create_commit() (
+	repo=$1
+	commit=$2
+	cd "$repo"
+	mkdir -p $(dirname "$commit") \
+	|| error "Could not create directory for commit"
+	echo "$commit" >"$commit"
+	git add "$commit" || error "Could not add commit"
+	git commit -m "$commit" || error "Could not commit"
+)
+
+last_commit_message()
+{
+	git log --pretty=format:%s -1
+}
+
+subtree_test_count=0
+next_test() {
+	subtree_test_count=$(($subtree_test_count+1))
+}
+
+#
+# Tests for 'git subtree add'
+#
+
+next_test
+test_expect_success 'no merge from non-existent subtree' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		test_must_fail git subtree merge --prefix="sub dir" FETCH_HEAD
+	)
+'
+
+next_test
+test_expect_success 'no pull from non-existent subtree' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		test_must_fail git subtree pull --prefix="sub dir" ./"sub proj" master
+	)'
+
+next_test
+test_expect_success 'add subproj as subtree into sub dir/ with --prefix' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Add '\''sub dir/'\'' from commit '\''$(git rev-parse FETCH_HEAD)'\''"
+	)
+'
+
+next_test
+test_expect_success 'add subproj as subtree into sub dir/ with --prefix and --message' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" --message="Added subproject" FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Added subproject"
+	)
+'
+
+next_test
+test_expect_success 'add subproj as subtree into sub dir/ with --prefix as -P and --message as -m' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add -P "sub dir" -m "Added subproject" FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Added subproject"
+	)
+'
+
+next_test
+test_expect_success 'add subproj as subtree into sub dir/ with --squash and --prefix and --message' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" --message="Added subproject with squash" --squash FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Added subproject with squash"
+	)
+'
+
+#
+# Tests for 'git subtree merge'
+#
+
+next_test
+test_expect_success 'merge new subproj history into sub dir/ with --prefix' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Merge commit '\''$(git rev-parse FETCH_HEAD)'\''"
+	)
+'
+
+next_test
+test_expect_success 'merge new subproj history into sub dir/ with --prefix and --message' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" --message="Merged changes from subproject" FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Merged changes from subproject"
+	)
+'
+
+next_test
+test_expect_success 'merge new subproj history into sub dir/ with --squash and --prefix and --message' '
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	subtree_test_create_repo "$subtree_test_count" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" --message="Merged changes from subproject using squash" --squash FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Merged changes from subproject using squash"
+	)
+'
+
+next_test
+test_expect_success 'merge the added subproj again, should do nothing' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD &&
+		# this shouldn not actually do anything, since FETCH_HEAD
+		# is already a parent
+		result=$(git merge -s ours -m "merge -s -ours" FETCH_HEAD) &&
+		check_equal "${result}" "Already up-to-date."
+	)
+'
+
+next_test
+test_expect_success 'merge new subproj history into subdir/ with a slash appended to the argument of --prefix' '
+	test_create_repo "$test_count" &&
+	test_create_repo "$test_count/subproj" &&
+	test_create_commit "$test_count" main1 &&
+	test_create_commit "$test_count/subproj" sub1 &&
+	(
+		cd "$test_count" &&
+		git fetch ./subproj master &&
+		git subtree add --prefix=subdir/ FETCH_HEAD
+	) &&
+	test_create_commit "$test_count/subproj" sub2 &&
+	(
+		cd "$test_count" &&
+		git fetch ./subproj master &&
+		git subtree merge --prefix=subdir/ FETCH_HEAD &&
+		check_equal "$(last_commit_message)" "Merge commit '\''$(git rev-parse FETCH_HEAD)'\''"
+	)
+'
+
+#
+# Tests for 'git subtree split'
+#
+
+next_test
+test_expect_success 'split requires option --prefix' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD &&
+		echo "You must provide the --prefix option." > expected &&
+		test_must_fail git subtree split > actual 2>&1 &&
+		test_debug "printf '"expected: "'" &&
+		test_debug "cat expected" &&
+		test_debug "printf '"actual: "'" &&
+		test_debug "cat actual" &&
+		test_cmp expected actual
+	)
+'
+
+next_test
+test_expect_success 'split requires path given by option --prefix must exist' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD &&
+		echo "'\''non-existent-directory'\'' does not exist; use '\''git subtree add'\''" > expected &&
+		test_must_fail git subtree split --prefix=non-existent-directory > actual 2>&1 &&
+		test_debug "printf '"expected: "'" &&
+		test_debug "cat expected" &&
+		test_debug "printf '"actual: "'" &&
+		test_debug "cat actual" &&
+		test_cmp expected actual
+	)
+'
+
+next_test
+test_expect_success 'split sub dir/ with --rejoin' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		split_hash=$(git subtree split --prefix="sub dir" --annotate="*") &&
+		git subtree split --prefix="sub dir" --annotate="*" --rejoin &&
+		check_equal "$(last_commit_message)" "Split '\''sub dir/'\'' into commit '\''$split_hash'\''"
+	)
+ '
+
+next_test
+test_expect_success 'split sub dir/ with --rejoin and --message' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --message="Split & rejoin" --annotate="*" --rejoin &&
+		check_equal "$(last_commit_message)" "Split & rejoin"
+	)
+'
+
+next_test
+test_expect_success 'split "sub dir"/ with --branch' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		split_hash=$(git subtree split --prefix="sub dir" --annotate="*") &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br &&
+		check_equal "$(git rev-parse subproj-br)" "$split_hash"
+	)
+'
+
+next_test
+test_expect_success 'check hash of split' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		split_hash=$(git subtree split --prefix="sub dir" --annotate="*") &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br &&
+		check_equal "$(git rev-parse subproj-br)" "$split_hash" &&
+		# Check hash of split
+		new_hash=$(git rev-parse subproj-br^2) &&
+		(
+			cd ./"sub proj" &&
+			subdir_hash=$(git rev-parse HEAD) &&
+			check_equal ''"$new_hash"'' "$subdir_hash"
+		)
+	)
+'
+
+next_test
+test_expect_success 'split "sub dir"/ with --branch for an existing branch' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git branch subproj-br FETCH_HEAD &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		split_hash=$(git subtree split --prefix="sub dir" --annotate="*") &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br &&
+		check_equal "$(git rev-parse subproj-br)" "$split_hash"
+	)
+'
+
+next_test
+test_expect_success 'split "sub dir"/ with --branch for an incompatible branch' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git branch init HEAD &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		test_must_fail git subtree split --prefix="sub dir" --branch init
+	)
+'
+
+#
+# Validity checking
+#
+
+next_test
+test_expect_success 'make sure exactly the right set of files ends up in the subproj' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub3 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD &&
+
+		chks="sub1
+sub2
+sub3
+sub4" &&
+		chks_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chks
+TXT
+) &&
+		chkms="main-sub1
+main-sub2
+main-sub3
+main-sub4" &&
+		chkms_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chkms
+TXT
+) &&
+
+		subfiles=$(git ls-files) &&
+		check_equal "$subfiles" "$chkms
+$chks"
+	)
+'
+
+next_test
+test_expect_success 'make sure the subproj *only* contains commits that affect the "sub dir"' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub3 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD &&
+
+		chks="sub1
+sub2
+sub3
+sub4" &&
+		chks_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chks
+TXT
+) &&
+		chkms="main-sub1
+main-sub2
+main-sub3
+main-sub4" &&
+		chkms_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chkms
+TXT
+) &&
+		allchanges=$(git log --name-only --pretty=format:"" | sort | sed "/^$/d") &&
+		check_equal "$allchanges" "$chkms
+$chks"
+	)
+'
+
+next_test
+test_expect_success 'make sure exactly the right set of files ends up in the mainline' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub3 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree pull --prefix="sub dir" ./"sub proj" master &&
+
+		chkm="main1
+main2" &&
+		chks="sub1
+sub2
+sub3
+sub4" &&
+		chks_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chks
+TXT
+) &&
+		chkms="main-sub1
+main-sub2
+main-sub3
+main-sub4" &&
+		chkms_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chkms
+TXT
+) &&
+		mainfiles=$(git ls-files) &&
+		check_equal "$mainfiles" "$chkm
+$chkms_sub
+$chks_sub"
+)
+'
+
+next_test
+test_expect_success 'make sure each filename changed exactly once in the entire history' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git config log.date relative
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub3 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree pull --prefix="sub dir" ./"sub proj" master &&
+
+		chkm="main1
+main2" &&
+		chks="sub1
+sub2
+sub3
+sub4" &&
+		chks_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chks
+TXT
+) &&
+		chkms="main-sub1
+main-sub2
+main-sub3
+main-sub4" &&
+		chkms_sub=$(cat <<TXT | sed '\''s,^,sub dir/,'\''
+$chkms
+TXT
+) &&
+
+		# main-sub?? and /"sub dir"/main-sub?? both change, because those are the
+		# changes that were split into their own history.  And "sub dir"/sub?? never
+		# change, since they were *only* changed in the subtree branch.
+		allchanges=$(git log --name-only --pretty=format:"" | sort | sed "/^$/d") &&
+		expected=''"$(cat <<TXT | sort
+$chkms
+$chkm
+$chks
+$chkms_sub
+TXT
+)"'' &&
+		check_equal "$allchanges" "$expected"
+	)
+'
+
+next_test
+test_expect_success 'make sure the --rejoin commits never make it into subproj' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub3 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree pull --prefix="sub dir" ./"sub proj" master &&
+		check_equal "$(git log --pretty=format:"%s" HEAD^2 | grep -i split)" ""
+	)
+'
+
+next_test
+test_expect_success 'make sure no "git subtree" tagged commits make it into subproj' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub3 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		 git merge FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub4 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --annotate="*" --branch subproj-br --rejoin
+	) &&
+	(
+		cd "$subtree_test_count/sub proj" &&
+		git fetch .. subproj-br &&
+		git merge FETCH_HEAD
+	) &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree pull --prefix="sub dir" ./"sub proj" master &&
+
+		# They are meaningless to subproj since one side of the merge refers to the mainline
+		check_equal "$(git log --pretty=format:"%s%n%b" HEAD^2 | grep "git-subtree.*:")" ""
+	)
+'
+
+#
+# A new set of tests
+#
+
+next_test
+test_expect_success 'make sure "git subtree split" find the correct parent' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git branch subproj-ref FETCH_HEAD &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --branch subproj-br &&
+
+		# at this point, the new commit parent should be subproj-ref, if it is
+		# not, something went wrong (the "newparent" of "master~" commit should
+		# have been sub2, but it was not, because its cache was not set to
+		# itself)
+		check_equal "$(git log --pretty=format:%P -1 subproj-br)" "$(git rev-parse subproj-ref)"
+	)
+'
+
+next_test
+test_expect_success 'split a new subtree without --onto option' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --branch subproj-br
+	) &&
+	mkdir "$subtree_test_count"/"sub dir2" &&
+	test_create_commit "$subtree_test_count" "sub dir2"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+
+		# also test that we still can split out an entirely new subtree
+		# if the parent of the first commit in the tree is not empty,
+		# then the new subtree has accidently been attached to something
+		git subtree split --prefix="sub dir2" --branch subproj2-br &&
+		check_equal "$(git log --pretty=format:%P -1 subproj2-br)" ""
+	)
+'
+
+next_test
 test_expect_success 'verify one file change per commit' '
-	x= &&
-	list=''"$(git log --pretty=format:'"'commit: %H'"' | joincommits)"'' &&
-#	test_debug "echo HERE" &&
-#	test_debug "echo ''"$list"''" &&
-	(git log --pretty=format:'"'commit: %H'"' | joincommits |
-	(	while read commit a b; do
-			test_debug "echo Verifying commit "''"$commit"''
-			test_debug "echo a: "''"$a"''
-			test_debug "echo b: "''"$b"''
-			check_equal "$b" ""
-			x=1
-		done
-		check_equal "$x" 1
-	))
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git branch sub1 FETCH_HEAD &&
+		git subtree add --prefix="sub dir" sub1
+	) &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir" --branch subproj-br
+	) &&
+	mkdir "$subtree_test_count"/"sub dir2" &&
+	test_create_commit "$subtree_test_count" "sub dir2"/main-sub2 &&
+	(
+		cd "$subtree_test_count" &&
+		git subtree split --prefix="sub dir2" --branch subproj2-br &&
+
+		x= &&
+		git log --pretty=format:"commit: %H" | join_commits |
+		(
+			while read commit a b; do
+				test_debug "echo Verifying commit $commit"
+				test_debug "echo a: $a"
+				test_debug "echo b: $b"
+				check_equal "$b" ""
+				x=1
+			done
+			check_equal "$x" 1
+		)
+	)
 '
 
-# test push
-
-cd ../..
-
-mkdir test-push
-
-cd test-push
-
-test_expect_success 'init main' '
-	test_create_repo main
-'
-
-test_expect_success 'init sub' '
-	test_create_repo "sub project"
-'
-
-cd ./"sub project"
-
-test_expect_success 'add subproject' '
-	create "sub project" &&
-	git commit -m "Sub project: 1" &&
-	git branch sub-branch-1
-'
-
-cd ../main
-
-test_expect_success 'make first commit and add subproject' '
-	create "main-1" &&
-	git commit -m "main: 1" &&
-	git subtree add "../sub project" --prefix "sub dir" --message "Added subproject" sub-branch-1 &&
-	check_equal "$(last_commit_message)" "Added subproject"
-'
-
-test_expect_success 'make second commit to a subproject file and push it into a sub project' '
-	create "sub dir/sub1" &&
-	git commit -m "Sub project: 2" &&
-	git subtree push "../sub project" --prefix "sub dir" sub-branch-1
-'
-
-cd ../"sub project"
-
-test_expect_success 'Test second commit is pushed' '
-	git checkout sub-branch-1 &&
-	check_equal "$(last_commit_message)" "Sub project: 2"
+next_test
+test_expect_success 'push split to subproj' '
+	subtree_test_create_repo "$subtree_test_count" &&
+	subtree_test_create_repo "$subtree_test_count/sub proj" &&
+	test_create_commit "$subtree_test_count" main1 &&
+	test_create_commit "$subtree_test_count/sub proj" sub1 &&
+	(
+		cd "$subtree_test_count" &&
+		git fetch ./"sub proj" master &&
+		git subtree add --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub1 &&
+	test_create_commit "$subtree_test_count" main2 &&
+	test_create_commit "$subtree_test_count/sub proj" sub2 &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub2 &&
+	(
+		cd $subtree_test_count/"sub proj" &&
+                git branch sub-branch-1 &&
+                cd .. &&
+		git fetch ./"sub proj" master &&
+		git subtree merge --prefix="sub dir" FETCH_HEAD
+	) &&
+	test_create_commit "$subtree_test_count" "sub dir"/main-sub3 &&
+        (
+		cd "$subtree_test_count" &&
+	        git subtree push ./"sub proj" --prefix "sub dir" sub-branch-1 &&
+                cd ./"sub proj" &&
+                git checkout sub-branch-1 &&
+         	check_equal "$(last_commit_message)" "sub dir/main-sub3"
+	)
 '
 
 test_done