我使用 pytest 和 pytest-xdist 来测试 django 应用程序，当我运行时py.test -n 1出现错误：
Test session starts (platform: linux2, Python 2.7.12, pytest 2.9.2, pytest-sugar 0.7.1)
django settings: icbase.settings (from ini file)
rootdir: /home/xsy/icgoo_git/datacenter3, inifile: pytest.ini
plugins: sugar-0.7.1, xdist-1.15.0, cov-2.3.1, django-2.9.1
gw0 okINTERNALERROR> Traceback (most recent call last):
INTERNALERROR> File "/home/xsy/.virtualenvs/dc3/lib/python2.7/site-packages/_pytest/main.py", line 94, in wrap_session
INTERNALERROR> session.exitstatus = doit(config, session) or 0
INTERNALERROR> File "/home/xsy/.virtualenvs/dc3/lib/python2.7/site-packages/_pytest/main.py", line 125, in _main
INTERNALERROR> config.hook.pytest_runtestloop(session=session)
INTERNALERROR> File "/home/xsy/.virtualenvs/dc3/lib/python2.7/site-packages/_pytest/vendored_packages/pluggy.py", line 724, in __call__
INTERNALERROR> return self._hookexec(self, self._nonwrappers + self._wrappers, …