git-am: record full index line in the patch used while rebasing

Earlier, a230949 (am --rebasing: get patch body from commit, not
from mailbox, 2012-06-26) learned to regenerate patch body from the
commit object while rebasing, instead of reading from the rebase-am
front-end.  While doing so, it used "git diff-tree" but without
giving it the "--full-index" option.

This does not matter for in-repository objects; during rebasing, any
abbreviated object name should uniquely identify them.

But we may be rebasing a commit that contains a change to a gitlink,
in which case we usually should not have the object (it names a
commit in the submodule).  A full object name is necessary to later
reconstruct a fake ancestor index for them.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

git-am.sh

@@ -664,7 +664,7 @@ do
 			sed -e '1,/^$/d' >"$dotest/msg-clean"
 			echo "$commit" >"$dotest/original-commit"
 			get_author_ident_from_commit "$commit" >"$dotest/author-script"
-			git diff-tree --root --binary "$commit" >"$dotest/patch"
+			git diff-tree --root --binary --full-index "$commit" >"$dotest/patch"
 		else
 			git mailinfo $keep $no_inbody_headers $scissors $utf8 "$dotest/msg" "$dotest/patch" \
 				<"$dotest/$msgnum" >"$dotest/info" ||

t/t7402-submodule-rebase.sh

@@ -3,7 +3,7 @@
 # Copyright (c) 2008 Johannes Schindelin
 #
 
-test_description='Test rebasing and stashing with dirty submodules'
+test_description='Test rebasing, stashing, etc. with submodules'
 
 . ./test-lib.sh
 
@@ -20,7 +20,8 @@ test_expect_success setup '
 	echo second line >> file &&
 	(cd submodule && git pull) &&
 	test_tick &&
-	git commit -m file-and-submodule -a
+	git commit -m file-and-submodule -a &&
+	git branch added-submodule
 
 '
 
@@ -89,4 +90,29 @@ test_expect_success 'stash with a dirty submodule' '
 
 '
 
+test_expect_success 'rebasing submodule that should conflict' '
+	git reset --hard &&
+	git checkout added-submodule &&
+	git add submodule &&
+	test_tick &&
+	git commit -m third &&
+	(
+		cd submodule &&
+		git commit --allow-empty -m extra
+	) &&
+	git add submodule &&
+	test_tick &&
+	git commit -m fourth &&
+
+	test_must_fail git rebase --onto HEAD^^ HEAD^ HEAD^0 &&
+	git ls-files -s submodule >actual &&
+	(
+		cd submodule &&
+		echo "160000 $(git rev-parse HEAD^) 1	submodule" &&
+		echo "160000 $(git rev-parse HEAD^^) 2	submodule" &&
+		echo "160000 $(git rev-parse HEAD) 3	submodule"
+	) >expect &&
+	test_cmp expect actual
+'
+
 test_done