list-objects-filter-options: do not over-strbuf_init

The function gently_parse_list_objects_filter is either called with
errbuf=STRBUF_INIT or errbuf=NULL, but that function calls strbuf_init
when errbuf is not NULL. strbuf_init is only necessary if errbuf
contains garbage, and risks a memory leak if errbuf already has a
non-STRBUF_INIT state. It should be the caller's responsibility to make
sure errbuf is not garbage, since garbage content is easily avoidable
with STRBUF_INIT.

Signed-off-by: Matthew DeVore <matvore@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

list-objects-filter-options.c

@@ -30,7 +30,6 @@ static int gently_parse_list_objects_filter(
 
 	if (filter_options->choice) {
 		if (errbuf) {
-			strbuf_init(errbuf, 0);
 			strbuf_addstr(
 				errbuf,
 				_("multiple filter-specs cannot be combined"));
@@ -71,10 +70,9 @@ static int gently_parse_list_objects_filter(
 		return 0;
 	}
 
-	if (errbuf) {
-		strbuf_init(errbuf, 0);
+	if (errbuf)
 		strbuf_addf(errbuf, "invalid filter-spec '%s'", arg);
-	}
+
 	memset(filter_options, 0, sizeof(*filter_options));
 	return 1;
 }