git-grep: correct exit code with --quiet and -L

The handling of `status_only` no longer interferes with the handling of
`unmatch_name_only`.  `--quiet` no longer affects the exit code when using
`-L`/`--files-without-match`.

Signed-off-by: Anthony Sottile <asottile@umich.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

grep.c

@@ -1629,7 +1629,7 @@ static int grep_source_1(struct grep_opt *opt, struct grep_source *gs, int colle
 		return 0;
 
 	if (opt->status_only)
-		return 0;
+		return opt->unmatch_name_only;
 	if (opt->unmatch_name_only) {
 		/* We did not see any hit, so we want to show this */
 		show_name(opt, gs->name);

t/t7810-grep.sh

@@ -370,6 +370,11 @@ test_expect_success 'grep -L -C' '
 	test_cmp expected actual
 '
 
+test_expect_success 'grep --files-without-match --quiet' '
+	git grep --files-without-match --quiet nonexistent_string >actual &&
+	test_cmp /dev/null actual
+'
+
 cat >expected <<EOF
 file:foo mmap bar_mmap
 EOF