Add a test for merging changed and rename-changed branches

Also leave a warning for future merge-recursive explorers.
Signed-off-by: NAlex Riesen <raa.lkml@gmail.com>
Signed-off-by: NJunio C Hamano <junkio@cox.net>

merge-recursive.c

@@ -1345,6 +1345,11 @@ static int process_renames(struct path_list *a_renames,
 				if (mfi.merge && mfi.clean &&
 				    sha_eq(mfi.sha, ren1->pair->two->sha1) &&
 				    mfi.mode == ren1->pair->two->mode)
+					/*
+					 * This messaged is part of
+					 * t6022 test. If you change
+					 * it update the test too.
+					 */
 					output(3, "Skipped %s (merged same as existing)", ren1_dst);
 				else {
 					if (mfi.merge || !mfi.clean)

t/t6022-merge-rename.sh

@@ -47,6 +47,8 @@ git branch white &&
 git branch red &&
 git branch blue &&
 git branch yellow &&
+git branch change &&
+git branch change+rename &&
 
 sed -e "/^g /s/.*/g : master changes a line/" <A >A+ &&
 mv A+ A &&
@@ -77,6 +79,17 @@ rm -f A M &&
 git update-index --add --remove A C M N &&
 git commit -m "blue renames A->C, M->N" &&
 
+git checkout change &&
+sed -e "/^g /s/.*/g : changed line/" <A >A+ &&
+mv A+ A &&
+git commit -q -a -m "changed" &&
+
+git checkout change+rename &&
+sed -e "/^g /s/.*/g : changed line/" <A >B &&
+rm A &&
+git update-index --add B &&
+git commit -q -a -m "changed and renamed" &&
+
 git checkout master'
 
 test_expect_success 'pull renaming branch into unrenaming one' \
@@ -318,4 +331,14 @@ test_expect_success 'interference with untracked working tree file' '
 	git reset --hard anchor
 '
 
+test_expect_success 'merge of identical changes in a renamed file' '
+	rm -f A M N
+	git reset --hard &&
+	git checkout change+rename &&
+	GIT_MERGE_VERBOSITY=3 git merge change | grep "^Skipped B" &&
+	git reset --hard HEAD^ &&
+	git checkout change &&
+	GIT_MERGE_VERBOSITY=3 git merge change+rename | grep "^Skipped B"
+'
+
 test_done