Merge branch 'jc/alternate-push'

* jc/alternate-push:
  push: receiver end advertises refs from alternate repositories
  push: prepare sender to receive extended ref information from the receiver
  receive-pack: make it a builtin
  is_directory(): a generic helper function

builtin-fetch-pack.c

@@ -735,7 +735,7 @@ int cmd_fetch_pack(int argc, const char **argv, const char *prefix)
 	conn = git_connect(fd, (char *)dest, args.uploadpack,
 			   args.verbose ? CONNECT_VERBOSE : 0);
 	if (conn) {
-		get_remote_heads(fd[0], &ref, 0, NULL, 0);
+		get_remote_heads(fd[0], &ref, 0, NULL, 0, NULL);
 
 		ref = fetch_pack(&args, fd, conn, ref, dest, nr_heads, heads, NULL);
 		close(fd[0]);