Free the path_lists used to find non-local tags in git-fetch

To support calling find_non_local_tags() more than once in a single
git-fetch process we need the existing_refs to be stack-allocated
so it resets on the second call.  We also should free the path
lists to avoid unnecessary memory leaking.

Signed-off-by: Shawn O. Pearce <spearce@spearce.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

builtin-fetch.c

@@ -457,7 +457,7 @@ static void find_non_local_tags(struct transport *transport,
 			struct ref **head,
 			struct ref ***tail)
 {
-	static struct path_list existing_refs = { NULL, 0, 0, 0 };
+	struct path_list existing_refs = { NULL, 0, 0, 0 };
 	struct path_list new_refs = { NULL, 0, 0, 1 };
 	char *ref_name;
 	int ref_name_len;
@@ -503,6 +503,8 @@ static void find_non_local_tags(struct transport *transport,
 		}
 		free(ref_name);
 	}
+	path_list_clear(&existing_refs, 0);
+	path_list_clear(&new_refs, 0);
 }
 
 static int do_fetch(struct transport *transport,