This is a fork for that is used in DeepProbLog to support approximate inference.
The most recent version of SWI-Prolog breaks this version of PySWIP. For Ubuntu, you can install version 8.4 from the official PPA (https://www.swi-prolog.org/build/PPA.html), using the following command:
apt-get install swi-prolog=8.4* swi-prolog-nox=8.4* swi-prolog-x=8.4*