Merge branch 'jt/push-negotiation-fixes' into maint

Bugfix for common ancestor negotiation recently introduced in "git
push" codepath.

* jt/push-negotiation-fixes:
  fetch: die on invalid --negotiation-tip hash
  send-pack: fix push nego. when remote has refs
  send-pack: fix push.negotiate with remote helper

builtin/fetch.c

@@ -1428,7 +1428,9 @@ static void add_negotiation_tips(struct git_transport_options *smart_options)
 		if (!has_glob_specials(s)) {
 			struct object_id oid;
 			if (get_oid(s, &oid))
-				die("%s is not a valid object", s);
+				die(_("%s is not a valid object"), s);
+			if (!has_object(the_repository, &oid, 0))
+				die(_("the object %s does not exist"), s);
 			oid_array_append(oids, &oid);
 			continue;
 		}

builtin/send-pack.c

@@ -230,6 +230,7 @@ int cmd_send_pack(int argc, const char **argv, const char *prefix)
 	args.atomic = atomic;
 	args.stateless_rpc = stateless_rpc;
 	args.push_options = push_options.nr ? &push_options : NULL;
+	args.url = dest;
 
 	if (from_stdin) {
 		if (args.stateless_rpc) {