fixup e7eb08d

I'm not sure how the '=' became a comma, I could have sworn I
typed '='. Also strange that it compiled, and that the commit
appeared to help the bug...

src/savegame.cpp

@@ -707,7 +707,7 @@ void loadgame::fill_mplevel_config(config& level){
 	// is empty the starting position contains the wanted info.
 	const config& start_data = !gamestate_.snapshot.empty() ? gamestate_.snapshot : gamestate_.replay_start();
 
-	level["map_data"], start_data["map_data"];
+	level["map_data"] = start_data["map_data"];
 	level["id"] = start_data["id"];
 	level["name"] = start_data["name"];
 	level["completion"] = start_data["completion"];