run deferred.py

    def _runDeferred(self, deferred, timeout, debug):
        """
        Does the actual deferred execution.
        """
        if not deferred.called:
            deferred_done = False
            while not deferred_done:
                self._iterateTestReactor(debug=debug)
                deferred_done = deferred.called

                if self._timeout_reached:
                    raise AssertionError(
                        'Deferred took more than %d to execute.' % timeout)

        result = deferred.result
        if isinstance(result, Deferred):
            self._runDeferred(result, timeout=timeout, debug=debug)
            result = deferred.result
            if isinstance(result, Deferred):
                self._runDeferred(result, timeout=timeout, debug=debug)