Allow builtin-fetch's find_non_local_tags to append onto a list

By allowing the function to append onto the end of an existing list
we can do more interesting things, like join the list of tags we
want to fetch into the first fetch, rather than the second.

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

builtin-fetch.c

@@ -453,7 +453,9 @@ static int add_existing(const char *refname, const unsigned char *sha1,
 	return 0;
 }
 
-static struct ref *find_non_local_tags(struct transport *transport)
+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 new_refs = { NULL, 0, 0, 1 };
@@ -462,8 +464,6 @@ static struct ref *find_non_local_tags(struct transport *transport)
 	const unsigned char *ref_sha1;
 	const struct ref *tag_ref;
 	struct ref *rm = NULL;
-	struct ref *ref_map = NULL;
-	struct ref **tail = &ref_map;
 	const struct ref *ref;
 
 	for_each_ref(add_existing, &existing_refs);
@@ -498,13 +498,11 @@ static struct ref *find_non_local_tags(struct transport *transport)
 			strcpy(rm->peer_ref->name, ref_name);
 			hashcpy(rm->old_sha1, ref_sha1);
 
-			*tail = rm;
-			tail = &rm->next;
+			**tail = rm;
+			*tail = &rm->next;
 		}
 		free(ref_name);
 	}
-
-	return ref_map;
 }
 
 static int do_fetch(struct transport *transport,
@@ -546,7 +544,9 @@ static int do_fetch(struct transport *transport,
 	/* if neither --no-tags nor --tags was specified, do automated tag
 	 * following ... */
 	if (tags == TAGS_DEFAULT && autotags) {
-		ref_map = find_non_local_tags(transport);
+		struct ref **tail = &ref_map;
+		ref_map = NULL;
+		find_non_local_tags(transport, &ref_map, &tail);
 		if (ref_map) {
 			transport_set_option(transport, TRANS_OPT_DEPTH, "0");
 			fetch_refs(transport, ref_map);