send-pack.c: move "no refs in common" abort earlier

Move the early return if we have no remote refs in send_pack()
earlier.

When this was added in 4c353e8 (Warn when send-pack does nothing,
2005-12-04) one of the first things we'd do was to abort, but as of
cfee10a (send-pack/receive-pack: allow errors to be reported back
to pusher., 2005-12-25) we've added numerous server_supports()
conditions that are acted on later in the function, that won't be used
if we don't have remote refs.

Then as of 477673d (send-pack: support push negotiation,
2021-05-04) we started doing even more work on the assumption that we
had some remote refs to feed to --negotiation-tip=* options.

We only hit this condition if we have nothing to push, so we don't
need to consider "push.negotiate" etc. only to do nothing with that
information.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

send-pack.c

@@ -486,6 +486,12 @@ int send_pack(struct send_pack_args *args,
 	const char *push_cert_nonce = NULL;
 	struct packet_reader reader;
 
+	if (!remote_refs) {
+		fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
+			"Perhaps you should specify a branch.\n");
+		return 0;
+	}
+
 	git_config_get_bool("push.negotiate", &push_negotiate);
 	if (push_negotiate)
 		get_commons_through_negotiation(args->url, remote_refs, &commons);
@@ -534,11 +540,6 @@ int send_pack(struct send_pack_args *args,
 		}
 	}
 
-	if (!remote_refs) {
-		fprintf(stderr, "No refs in common and none specified; doing nothing.\n"
-			"Perhaps you should specify a branch.\n");
-		return 0;
-	}
 	if (args->atomic && !atomic_supported)
 		die(_("the receiving end does not support --atomic push"));