Merge pull request #8652 from Mailaender/custom-rule-warning

Added a warning about custom game rules

OpenRA.Mods.Common/ServerTraits/LobbyCommands.cs

@@ -371,6 +371,9 @@ namespace OpenRA.Mods.Common.Server
 
 						server.SendMessage("{0} changed the map to {1}.".F(client.Name, server.Map.Title));
 
+						if (server.Map.RuleDefinitions.Any())
+							server.SendMessage("This map contains custom rules. Game experience may change.");
+
 						return true;
 					}
 				},