Fairyground: AI does not move in my a9-chess variant

[djbclark]

On Fairyground, when used with my a9-chess variant, the AI does not move, it just loses on time.

Closest I could find to it is cross-derby, the AI works fine with that.

Also of possible interest, a9-chess crashes WinBoard and FairyFishGui.

# This is normal chess except the square a9 exists.
# Pawn still promotes on the a8 square.
# Qa9 is the joke name for Maynard High School's Chess Team.
# This exists to help with problem composition where Qa9! is the winning move.
[a9-chess:chess]
maxRank = 9
startFen = 1*******/rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1

[ianfab]

If you remove the black castling rights it works. There might be some gap in FEN validation that causes this to crash. There is a castlingRank property that defines on which relative rank the castling happens, and by default it is the first rank. Making both sides being able to castle on different ranks might not be configurable at the moment.