Fix a divide by zero crash in Move.

OpenRA.Mods.Common/Activities/Move/Move.cs

@@ -414,6 +414,11 @@ namespace OpenRA.Mods.Common.Activities
 					// The center of rotation is where the normal vectors cross
 					var u = new WVec(1024, 0, 0).Rotate(WRot.FromYaw(fromFacing));
 					var v = new WVec(1024, 0, 0).Rotate(WRot.FromYaw(toFacing));
+
+					// Make sure that u and v aren't parallel, which may happen due to rounding
+					// in WVec.Rotate if delta is close but not necessarily equal to 0 or 512
+					if (v.X * u.Y != v.Y * u.X)
+					{
 						var w = from - to;
 						var s = (v.Y * w.X - v.X * w.Y) * 1024 / (v.X * u.Y - v.Y * u.X);
 						var x = from.X + s * u.X / 1024;
@@ -427,6 +432,7 @@ namespace OpenRA.Mods.Common.Activities
 						EnableArc = true;
 					}
 				}
+			}
 
 			public override bool Tick(Actor self)
 			{