Message6134

OK, I think we've found where the problem was introduced:

Revision 6837
hack around PyReflectedFunction's assumption of how instancemethod calls into
it so instancemethod's ThreadState pass through optimization can be enabled

The problem is in PyReflectedFunction.java, in this method: 
public PyObject __call__(PyObject[] args, String[] keywords) {
(it's line 194 in revision 7066).

I don't have enough understanding of how all this fits together to suggest a fix (the comment in line 48
    // NOTE: this calledStatically business is pretty hacky
suggests only the brave should touch this code).

However, I hope that's enough to get you started.