https://bugzilla.wikimedia.org/show_bug.cgi?id=72680
--- Comment #10 from Merlijn van Deen valhallasw@arctus.nl --- As a workaround, chdir to the pwb.py path before running, or explicitly define the user-config path with -dir:/path/where/pwb.py/is (or check out an older revision).
As far as I can see, the merged patch fixes this. The behaviour /is/ slightly different from before (the current working dir gets prevalence over the pwb.py directory) but this is by design.