I have found 6 open source rule engines written in Python, all of them dead (in terms of recent commits), except maybe one:
https://lab.abilian.com/Tech/Programming%20Techniques/Rule-b...
https://lab.abilian.com/Tech/Programming%20Techniques/Rule-b...
Also for your consideration, clipspy, which exposes CLIPS in Python: https://github.com/noxdafox/clipspy