fix lingering in mp

src/playmp_controller.cpp

@@ -417,7 +417,8 @@ void playmp_controller::maybe_linger()
 	// mouse_handler expects at least one team for linger mode to work.
 	assert(is_regular_game_end());
 	if (!get_end_level_data_const().transient.linger_mode || gamestate().board_.teams().empty() || gui_->video().faked()) {
-		if(!is_host()) {
+		const bool has_next_scenario = !gamestate().gamedata_.next_scenario().empty() && gamestate().gamedata_.next_scenario() != "null";
+		if(!is_host() && has_next_scenario) {
 			// If we continue without lingering we need to
 			// make sure the host uploads the next scenario
 			// before we attempt to download it.