Comment 3 for bug 1711346

Here's the simplest failing test example I could come up with, which is close to 'hello world' for prolog :

$ prolog
GNU Prolog 1.4.5 (64 bits)
Compiled Feb 5 2017, 10:30:08 with gcc
By Daniel Diaz
Copyright (C) 1999-2016 Daniel Diaz
| ?- [user].
compiling user for byte code...
p :- q(a).
q(a).

user compiled, 2 lines read - 294 bytes written, 13418 ms

yes
| ?- p.
uncaught exception: error(existence_error(procedure,q/0),p/0)
| ?-

On the query "?- p." gprolog should return with "yes", not the exception.