def service_update(self, ctxt, host_name, binary, params_to_update):
        cell_name, host_name = cells_utils.split_cell_and_item(host_name)
        response = self.msg_runner.service_update(
            ctxt, cell_name, host_name, binary, params_to_update)
        service = response.value_or_raise()
        service = cells_utils.add_cell_to_service(service, response.cell_name)
        return service
L{IReactorCore.addSystemEventTrigger} should accept the C{'before'}
dataset/ETHPy150Open BU-NU-CLOUD-SP16/Trusted-Platform-Module-nova/nova/cells/manager.py/CellsManager.service_update--crossover with--dataset/ETHPy150Open kuri65536/python-for-android/python-modules/twisted/twisted/test/test_internet.py/SystemEventTestCase.test_beforePhase