🚀 go-pugleaf

It seems that when playing gnuchess with xboard with me as white and
gnuchess as black, whenever I advance a pawn into the 7th rank,
gnuchess' next move (or any subsequent move as long as the pawn stays
in the 7th rank) is likely to be declared illegal by xboard. That is,
gnuchess' move flashes momentarily and then the message illegal move
is shown, followed by black's clock ticking away forever. The
"illegal" move is generally perfectly legal.

Here are a couple of example games--I think they're fairly closely
related. I played one other game today (quite different) that showed
the same behavior, but I didn't capture it.

xboard game file -- Thu Apr  4 12:52:13 1991
	vaughan@sunspot vs. ../gnuchessr@localhost
	algebraic
1. e2e4 c7c5
2. g1f3 d7d6
3. d2d4 c5d4
4. f3d4 g8f6
5. b1c3 a7a6
6. f1e2 e7e5
7. d4b3 f8e7
8. e1g1 e8g8
9. c1e3 b8d7
10. f2f4 b7b6
11. e2d3 c8b7
12. f4f5 d8c7
13. g2g4 h7h6
14. h2h4 f8c8
15. g4g5 f6e8
16. d1h5 a8b8
17. g1f2 h6g5
18. h4g5 e7d8
19. f1h1 g8f8
20. h5h8 f8e7
21. h8g8 d6d5
22. g5g6 e8d6
23. e4d5 d7f6
24. e3g5 e7d7
25. g8g7 d8e7
26. g6f7 b6b5

b6b5 was declared illegal


xboard game file -- Wed Apr  3 12:45:28 1991
	vaughan@sunspot vs. ../gnuchessr@localhost
	algebraic
1. e2e4 c7c5
2. g1f3 d7d6
3. d2d4 c5d4
4. f3d4 g8f6
5. b1c3 a7a6
6. f1e2 e7e5
7. d4b3 f8e7
8. e1g1 e8g8
9. c1e3 b8d7
10. f2f4 b7b6
11. f4f5 c8b7
12. e2d3 d8c7
13. g2g4 h7h6
14. h2h4 f8c8
15. g4g5 f6e8
16. d1h5 a8b8
17. g1f2 h6g5
18. h4g5 e7d8
19. f1h1 g8f8
20. h5h8 f8e7
21. h8g8 d7c5 --- differs here
22. g5g6 c5d3
23. c2d3 e7d7
24. g6f7 e8f6

e8f6 was declared illegal.

I notice that when I use gnuchess alone I can rarely get it to play
the same moves without using force, but when it does play the same
moves, the output seems perfectly normal.

 Paul Vaughan, MCC CAD Program | ARPA: vaughan@mcc.com | Phone: [512] 338-3639
 Box 200195, Austin, TX 78720  | UUCP: ...!cs.utexas.edu!milano!cadillac!vaughan
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