commit: allow partial commits with relative paths

Commit 8894d53580 (commit: allow partial commits with relative paths, 2011-07-30) ensured that partial commits were allowed when a user supplies a relative pathspec but then this was regressed in 5879f5684c (remove prefix argument from pathspec_prefix, 2011-09-04) when the prefix argument to 'pathspec_prefix' removed and the 'list_paths' function wasn't properly adjusted to cope with the change, resulting in over-eager pruning of the tree that is overlayed on the index.

This fixes the regression and adds a regression test so this can be prevented in the future.

---
 builtin/commit.c  |  3 +--
 t/t7501-commit.sh | 12 ++++++++++++
 2 files changed, 13 insertions(+), 2 deletions(-)

index 37fcb55ab0..5571d4a3e2 100644
@@ -218,8 +218,7 @@ static int list_paths(struct string_list *list, const char *with_tree,
 
 	if (with_tree) {
 		char *max_prefix = common_prefix(pattern);
-		overlay_tree_on_index(&the_index, with_tree,
-				      max_prefix ? max_prefix : prefix);
+		overlay_tree_on_index(&the_index, with_tree, max_prefix);
 		free(max_prefix);
 	}
 

index fa61b1a4ee..9dbbd01fc0 100755
@@ -52,6 +52,18 @@ test_expect_success PERL 'can use paths with --interactive' '
 	git reset --hard HEAD^
 '
 
+test_expect_success 'removed files and relative paths' '
+	test_when_finished "rm -rf foo" &&
+	git init foo &&
+	>foo/foo.txt &&
+	git -C foo add foo.txt &&
+	git -C foo commit -m first &&
+	git -C foo rm foo.txt &&
+
+	mkdir -p foo/bar &&
+	git -C foo/bar commit -m second ../foo.txt
+'
+
 test_expect_success 'using invalid commit with -C' '
 	test_must_fail git commit --allow-empty -C bogus
 '

2.17.0.rc1.321.gba9d0f2565-goog