subtree: t7900: delete some dead code

Signed-off-by: Luke Shumaker <lukeshu@datawire.io>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/subtree/t/t7900-subtree.sh

@@ -10,7 +10,6 @@ and split subcommands of git subtree.
 '
 
 TEST_DIRECTORY=$(pwd)/../../../t
-export TEST_DIRECTORY
 . "$TEST_DIRECTORY"/test-lib.sh
 
 # Use our own wrapper around test-lib.sh's test_create_repo, in order
@@ -23,15 +22,6 @@ subtree_test_create_repo () {
 	git -C "$1" config log.date relative
 }
 
-create () {
-	echo "$1" >"$1" &&
-	git add "$1"
-}
-
-undo () {
-	git reset --hard HEAD~
-}
-
 # Make sure no patch changes more than one file.
 # The original set of commits changed only one file each.
 # A multi-file change would imply that we pruned commits
@@ -404,7 +394,7 @@ test_expect_success 'check hash of split' '
 		(
 			cd ./"sub proj" &&
 			subdir_hash=$(git rev-parse HEAD) &&
-			test ''"$new_hash"'' = "$subdir_hash"
+			test "$new_hash" = "$subdir_hash"
 		)
 	)
 '