Store return value and status of an executed task.

def _store_result(self, task_id, result, status,
                      traceback=None, request=None):
        """Store return value and status of an executed task."""
        self.TaskModel._default_manager.store_result(
            task_id, result, status,
            traceback=traceback, children=self.current_task_children(request),
        )
        return result