merge-recursive: ensure we write updates for directory-renamed file

When a file is present in HEAD before the merge and the other side of the
merge does not modify that file, we try to avoid re-writing the file and
making it stat-dirty.  However, when a file is present in HEAD before the
merge and was in a directory that was renamed by the other side of the
merge, we have to move the file to a new location and re-write it.
Update the code that checks whether we can skip the update to also work in
the presence of directory renames.

Reviewed-by: Stefan Beller <[email protected]>
Signed-off-by: Elijah Newren <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: newren

merge-recursive.c

@@ -2763,16 +2763,14 @@ static int merge_content(struct merge_options *o,
 
 	if (mfi.clean && !df_conflict_remains &&
 	    oid_eq(&mfi.oid, a_oid) && mfi.mode == a_mode) {
-		int path_renamed_outside_HEAD;
 		output(o, 3, _("Skipped %s (merged same as existing)"), path);
 		/*
 		 * The content merge resulted in the same file contents we
 		 * already had.  We can return early if those file contents
 		 * are recorded at the correct path (which may not be true
 		 * if the merge involves a rename).
 		 */
-		path_renamed_outside_HEAD = !path2 || !strcmp(path, path2);
-		if (!path_renamed_outside_HEAD) {
+		if (was_tracked(path)) {
 			add_cacheinfo(o, mfi.mode, &mfi.oid, path,
 				      0, (!o->call_depth), 0);
 			return mfi.clean;

t/t6043-merge-rename-directories.sh

@@ -3884,7 +3884,7 @@ test_expect_success '12b-setup: Moving one directory hierarchy into another' '
 	)
 '
 
-test_expect_failure '12b-check: Moving one directory hierarchy into another' '
+test_expect_success '12b-check: Moving one directory hierarchy into another' '
 	(
 		cd 12b &&