prune: quiet ENOENT on missing directories

$GIT_DIR/objects/pack may be removed to save inodes in shared
repositories.  Quiet down prune in cases where either
$GIT_DIR/objects or $GIT_DIR/objects/pack is non-existent,
but emit the system error in other cases to help users diagnose
permissions problems or resource constraints.

Signed-off-by: Eric Wong <e@80x24.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin/prune.c

@@ -127,7 +127,9 @@ static void remove_temporary_files(const char *path)
 
 	dir = opendir(path);
 	if (!dir) {
-		fprintf(stderr, "Unable to open directory %s\n", path);
+		if (errno != ENOENT)
+			fprintf(stderr, "Unable to open directory %s: %s\n",
+				path, strerror(errno));
 		return;
 	}
 	while ((de = readdir(dir)) != NULL)

t/t5304-prune.sh

@@ -29,6 +29,14 @@ test_expect_success setup '
 	git gc
 '
 
+test_expect_success 'bare repo prune is quiet without $GIT_DIR/objects/pack' '
+	git clone -q --shared --template= --bare . bare.git &&
+	rmdir bare.git/objects/pack &&
+	git --git-dir=bare.git prune --no-progress 2>prune.err &&
+	test_must_be_empty prune.err &&
+	rm -r bare.git prune.err
+'
+
 test_expect_success 'prune stale packs' '
 	orig_pack=$(echo .git/objects/pack/*.pack) &&
 	>.git/objects/tmp_1.pack &&