mailman scan_message exception

scan_message in mailman/app/bounces.py causes exception becuase:

    for detector_class in find_components('mailman.bouncers', IBounceDetector):
        addresses = detector().process(msg)

is not:

    for detector_class in find_components('mailman.bouncers', IBounceDetector):
        addresses = detector_class().process(msg)

I'am working around it by reimplementing the function in my code, but I would be happy if I don't need to, because it touches more internal interfaces than neccesarry.