merge-recursive: fix the refresh logic in update_file_flags

If we need to delete a higher stage entry in the index to place the file
at stage 0, then we'll lose that file's stat information.  In such
situations we may still be able to detect that the file on disk is the
version we want (as noted by our comment in the code:
  /* do not overwrite file if already present */
), but we do still need to update the mtime since we are creating a new
cache_entry for that file.  Update the logic used to determine whether
we refresh a file's mtime.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

merge-recursive.c

@@ -998,10 +998,13 @@ static int update_file_flags(struct merge_options *opt,
 		free(buf);
 	}
 update_index:
-	if (!ret && update_cache)
-		if (add_cacheinfo(opt, contents, path, 0, update_wd,
+	if (!ret && update_cache) {
+		int refresh = (!opt->priv->call_depth &&
+			       contents->mode != S_IFGITLINK);
+		if (add_cacheinfo(opt, contents, path, 0, refresh,
 				  ADD_CACHE_OK_TO_ADD))
 			return -1;
+	}
 	return ret;
 }
 

t/t3433-rebase-across-mode-change.sh

@@ -33,7 +33,7 @@ test_expect_success 'rebase changes with the apply backend' '
 	git rebase side1
 '
 
-test_expect_failure 'rebase changes with the merge backend' '
+test_expect_success 'rebase changes with the merge backend' '
 	test_when_finished "git rebase --abort || true" &&
 	git checkout -b merge-backend side2 &&
 	git rebase -m side1