circuitbuilder: stop getting a circuit to close it.

        raise NotImplementedError()

    def close_circuit(self, circ_id):

        c = self.controller

        try:

            c.get_circuit(circ_id, default=None)

        try:

                c.close_circuit(circ_id)

            self.controller.close_circuit(circ_id)

        # SocketClosed will be raised when stopping sbws

        except (InvalidArguments, InvalidRequest, SocketClosed) as e:

            log.debug(e)

        self.built_circuits.discard(circ_id)

        except (ControllerError, ValueError) as e:

            log.exception("Error trying to get circuit to close it: %s.", e)

    def _build_circuit_impl(self, path):

        """