Fix ReturnToBase restarting on each hotkey press

Now that the RTB process is a single activity with childs,
it's relatively easy to prevent the activity from restarting
every time the deploy/RTB hotkey is pressed.

OpenRA.Mods.Common/Traits/Air/Aircraft.cs

@@ -859,6 +859,10 @@ namespace OpenRA.Mods.Common.Traits
 			}
 			else if (order.OrderString == "ReturnToBase" && rearmable != null && rearmable.Info.RearmActors.Any())
 			{
+				// Don't restart activity every time deploy hotkey is triggered
+				if (self.CurrentActivity is ReturnToBase)
+					return;
+
 				if (!order.Queued)
 					UnReserve();