Hi Igor,
Thanks for your interest in GNU Chess and for reporting that problem.
Certainly, the segmentation fault is reproduced using GNU Chess 6.1.1. The reason is the 'Q' for queen in the promotion move 'f2g1Q'. The program only accepts lower case letters for pieces in promotion moves. Hence, if you replace that move by 'f2g1q', GNU Chess will happily accept your position and will keep on playing.
I will take note of it, as it would be nicer for a user to receive a complaint from the program rather than a segmentation fault.
Cheers,
Antonio