Comment 6 for bug 913991

Okay, I understand better what's happening here. I'm no pygi expert but the switch to pygi caused the code in gobject_service.py to fail due. Also, that code is not compatible with Python 3 due to different metaclass definition syntax. I've rewritten the code in gobject_service.py to use pygi and be compatible across Python versions. I've just committed the changes to my Py3 branch, but you might be able to tease out the differences if you want to apply this separately from that branch:

https://github.com/warsaw/dbus-python3/commit/f8dab5af0bef5d26a51df41a564a5285c16a9cb5