fix celery warm shutdown unack task.py

class CustomTask(Task):
    def on_failure(self, exc, task_id, args, kwargs, einfo):
        info = '[{0}] failed: {1}'.format(task_id, exc)
        logger.exception(info, exc_info=exc)
        super(CustomTask, self).on_failure(exc, task_id, args, kwargs, einfo)

    def on_success(self, retval, task_id, args, kwargs):
        global app
        if app.is_warm_shutdown:
            app.consumer.connection._default_channel.do_restore = False


# monkey patch Task to log exception
app.Task = CustomTask

app.config_from_object('conf.celery_settings')

app.autodiscover_tasks()

app.is_warm_shutdown = False


def mark_app_warm_shutdown(*args, **kwargs):
    global app
    logger.info('hook warm shutdown')
    app.is_warm_shutdown = True
    app.origin_signal_handler(*args, **kwargs)


@receiver(worker_ready)
def on_celery_worker_ready(sender, **kwargs):
    global app
    logger.info('hook work ready')
    app.consumer = sender
    app.origin_signal_handler = platforms.signals["TERM"]
    platforms.signals["TERM"] = mark_app_warm_shutdown