параллельный тест django возвращает ошибку multiprocessing.pool

Question

Когда я пытаюсь запустить мои тесты django на Travis CI параллельно, используя --parallel, я сталкиваюсь с этой ошибкой

Traceback (most recent call last):
  File "manage.py", line 43, in <module>
    execute_from_command_line(sys.argv)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/core/management/__init__.py", line 364, in execute_from_command_line
    utility.execute()
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/core/management/__init__.py", line 356, in execute
    self.fetch_command(subcommand).run_from_argv(self.argv)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/core/management/commands/test.py", line 29, in run_from_argv
    super(Command, self).run_from_argv(argv)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/core/management/base.py", line 283, in run_from_argv
    self.execute(*args, **cmd_options)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/core/management/base.py", line 330, in execute
    output = self.handle(*args, **options)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/core/management/commands/test.py", line 62, in handle
    failures = test_runner.run_tests(test_labels)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/test/runner.py", line 603, in run_tests
    result = self.run_suite(suite)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/test/runner.py", line 567, in run_suite
    return runner.run(suite)
  File "/opt/python/2.7.6/lib/python2.7/unittest/runner.py", line 151, in run
    test(result)
  File "/opt/python/2.7.6/lib/python2.7/unittest/suite.py", line 70, in __call__
    return self.run(*args, **kwds)
  File "/home/travis/virtualenv/python2.7.6/lib/python2.7/site-packages/django/test/runner.py", line 370, in run
    subsuite_index, events = test_results.next(timeout=0.1)
  File "/opt/python/2.7.6/lib/python2.7/multiprocessing/pool.py", line 655, in next
    raise value
TypeError: __init__() takes exactly 3 arguments (2 given)

Я не могу найти никакой поддержки с этим, и это в Django.

Я не знаю, какой третий аргумент init () ожидает в этом случае.

Моя версия django - 1.11.18

Командаpython manage.py test --parapllel=4