AttributeError：'NoneType'对象没有属性'loader'

今天启动笔记本电脑（Ubuntu 18.4）并尝试使用pip安装软件包时遇到问题，我遇到此错误：

Error processing line 3 of /home/cjones/.local/lib/python3.6/site-packages/googleapis_common_protos-1.5.8-py3.6-nspkg.pth:

  Traceback (most recent call last):
    File "/usr/lib/python3.6/site.py", line 174, in addpackage
      exec(line)
    File "<string>", line 1, in <module>
    File "<frozen importlib._bootstrap>", line 568, in module_from_spec
  AttributeError: 'NoneType' object has no attribute 'loader'

Remainder of file ignored

自上次成功启动以来，我认为我没有进行任何更改，但似乎缺少了某些东西……有人可以帮忙吗？