def METHOD_NAME(self, new_config):
    port = self._calculatePort(new_config)
    if not port:
        config.error("No port specified for PBChangeSource, and no "
                     "worker port configured")
    # and, if it's changed, re-register
    if port != self.registered_port and self.isActive():
        yield self._unregister()
        yield self._register(port)
    yield super().METHOD_NAME(new_config)