Celery 4.2.0 版本发现任务失败

Question

这是我用来启动芹菜的代码：

from celery import Celery
from foo.lib.config import app
from foo.mods.bar.tract import Tesser
from foo.mods.baz.commons import clean_data, quotify


celery_app = Celery(app.name, broker=app.config["CELERY_BROKER_URL"])
celery_app.conf.update(app.config)
celery_app.autodiscover_tasks()


@celery_app.task
def tract_task(content):
    return Tesser.tesseract(content)


@celery_app.task
def clean_data_task(content):
    return clean_data(content)


@celery_app.task
def quotify_task(content):
    return quotify(content)

我使用以下命令启动工作程序：

celery worker -A celery_tasks.celery_app -l=info

这以前可以完美运行，但是当我将 celery 升级到 4.2.0 时，出现以下错误：

Traceback (most recent call last):
  File "/home/minister/.local/bin/celery", line 11, in <module>
    sys.exit(main())
  File "/home/minister/.local/lib/python3.5/site-packages/celery/__main__.py", line 16, in main
    _main()
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/celery.py", line 322, in main
    cmd.execute_from_commandline(argv)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/celery.py", line 496, in execute_from_commandline
    super(CeleryCommand, self).execute_from_commandline(argv)))
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/base.py", line 275, in execute_from_commandline
    return self.handle_argv(self.prog_name, argv[1:])
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/celery.py", line 488, in handle_argv
    return self.execute(command, argv)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/celery.py", line 420, in execute
    ).run_from_argv(self.prog_name, argv[1:], command=argv[0])
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/worker.py", line 223, in run_from_argv
    return self(*args, **options)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/base.py", line 238, in __call__
    ret = self.run(*args, **kwargs)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/bin/worker.py", line 257, in run
    **kwargs)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/worker/worker.py", line 96, in __init__
    self.app.loader.init_worker()
  File "/home/minister/.local/lib/python3.5/site-packages/celery/loaders/base.py", line 114, in init_worker
    self.import_default_modules()
  File "/home/minister/.local/lib/python3.5/site-packages/celery/loaders/base.py", line 108, in import_default_modules
    raise response
  File "/home/minister/.local/lib/python3.5/site-packages/celery/utils/dispatch/signal.py", line 288, in send
    response = receiver(signal=self, sender=sender, **named)
  File "/home/minister/.local/lib/python3.5/site-packages/vine/promises.py", line 143, in __call__
    return self.throw()
  File "/home/minister/.local/lib/python3.5/site-packages/vine/promises.py", line 140, in __call__
    retval = fun(*final_args, **final_kwargs)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/app/base.py", line 673, in _autodiscover_tasks
    return self._autodiscover_tasks_from_fixups(related_name)
  File "/home/minister/.local/lib/python3.5/site-packages/celery/app/base.py", line 683, in _autodiscover_tasks_from_fixups
    pkg for fixup in self._fixups
  File "/home/minister/.local/lib/python3.5/site-packages/celery/app/base.py", line 684, in <listcomp>
    for pkg in fixup.autodiscover_tasks()
AttributeError: 'NoneType' object has no attribute 'autodiscover_tasks'

最新版本发生了什么变化，我的代码需要改变什么？这可能是一个错误。