PathFinder tries to go through unavailable rooms

[sparr]

The unavailable rooms across the middle of a novice zone have constructed walls in them instead of terrain walls. This means the PathFinder can't see them until I have vision of them. PathFinder also doesn't know to avoid unavailable rooms. So it ends up producing paths that lead to an impassable exit, where a creep will just sit, waiting for a border dance that never happens.

PathFinder should probably automatically skip not-Available rooms.