Merge "Cert: Check that child returns 0 or -signal"

    def clean_up(self):

        self.grpc_channel.close()

        self.grpc_root_server_channel.close()

        self.backing_process.send_signal(signal.SIGINT)

        stop_signal = signal.SIGINT

        self.backing_process.send_signal(stop_signal)

        backing_process_return_code = self.backing_process.wait()

        self.backing_process_logs.close()

        if backing_process_return_code != 0:

        if backing_process_return_code not in [-stop_signal, 0]:

            logging.error("backing process %s stopped with code: %d" %

                          (self.label, backing_process_return_code))

            return False