I tried to force a train to redo its pathfinding to enter a free lane in a train stacker (it just loved to go into the full lane

So I thought, if the chain signal the train is standing at changes from blue to red to blue, it hopefully recalculates its path.
That didn´t work, but I found a bug while doing so. The Chain signal does change its state, but doesnt show the correct color (its just a GUI-thing, the train will wait at the green signal).
Poorly it wont recalculate the path
