made Expand a bit more sensible

OpenRA.Game/PathSearch.cs

@@ -66,6 +66,8 @@ namespace OpenRA
 
 			if (thisCost == float.PositiveInfinity) 
 				return p.Location;
+
+			var bi = world.WorldActor.traits.Get<BuildingInfluence>();
 					
 			foreach( int2 d in directions )
 			{
@@ -81,8 +83,7 @@ namespace OpenRA
 				if (costHere == float.PositiveInfinity)
 					continue;
 
-				if (!world.WorldActor.traits.Get<BuildingInfluence>().CanMoveHere(newHere) && 
-					world.WorldActor.traits.Get<BuildingInfluence>().GetBuildingAt(newHere) != ignoreBuilding)
+				if (!bi.CanMoveHere(newHere, ignoreBuilding))
 					continue;
 
 				// Replicate real-ra behavior of not being able to enter a cell if there is a mixture of crushable and uncrushable units

OpenRA.Game/Traits/World/BuildingInfluence.cs

@@ -70,4 +70,10 @@ namespace OpenRA.Traits
 		{
 			return map.IsInMap(cell) && !blocked[cell.X, cell.Y];
 		}
+
+		public bool CanMoveHere(int2 cell, Actor toIgnore)
+		{
+			return map.IsInMap(cell) && 
+				(!blocked[cell.X, cell.Y] || influence[cell.X, cell.Y] == toIgnore);
+		}
 	}}