issue with single non-numerical character

[josd]

This program worked in the past (and for all prologs that I tested) but not in the more recent versions of Scryer. Replacing some of the # with the string "#" like in it works again:

$ scryer-prolog -g run,halt turing.pl
'https://josd.github.io/imagining#compute'([1,0,1,0,0,1],[1,0,1,0,1,0,"#"]).
'https://josd.github.io/imagining#compute'([1,0,1,1,1,1],[1,1,0,0,0,0,"#"]).
'https://josd.github.io/imagining#compute'([1,1,1,1,1,1],[1,0,0,0,0,0,0,"#"]).
'https://josd.github.io/imagining#compute'([],[1,"#"]).