[Bug-gnubg] Show Move moves the wrong pieces

[Ian Shaw]

Hey guys, 

I've just noticed weird behaviour with Show Move in a specific circumstance.
Here's how I was able to repeat it.

Start a game with manual dice.
Give yourself (bottom player) the opening roll.
Make a move.
Analyse the match at World Class.
Click on the move to select it and look at various moves using Show Move. The 
correct chequers are moved.
Select a move that missed the cut-off for 2-ply analysis. 
Analyse it at 2-ply.
Look at various moves using Show Move. The incorrect chequers are moved, 
including those that showed correctly before!

This behaviour only happens on the first move of the game, when player 1 
(bottom)  wins the opening roll. My guess would be that, during the second 
analysis, the indicator for who is on roll is getting messed up and defaulting 
back to player 0 or undefined. 

Cheers,
Ian Shaw