Pip 21.1 无法导入 InvalidSchemeCombination

在工作中，我们使用 Github 操作来构建和测试我们的 Pull 请求，然后才能获得批准。 周五下午，一切都进展顺利。 周一早上，所有测试都很早就失败了，错误显示 pip 无法再找到自己的异常。最新的 Pip 有什么变化吗？

正如您在下面的错误中看到的，我们自己的代码没有被引用，而且我相当确定周五和周一之间我们的流程没有任何变化（我们是一个小团队，批准的 PR 没有任何令人惊讶的地方） ）。

错误回溯：

Traceback (most recent call last):
    File "/opt/hostedtoolcache/Python/3.7.9/x64/bin/pip", line 5, in <module>
      from pip._internal.cli.main import main
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/cli/main.py", line 8, in <module>
      from pip._internal.cli.autocompletion import autocomplete
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/cli/autocompletion.py", line 9, in <module>
      from pip._internal.cli.main_parser import create_main_parser
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/cli/main_parser.py", line 7, in <module>
      from pip._internal.cli import cmdoptions
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/cli/cmdoptions.py", line 22, in <module>
      from pip._internal.cli.progress_bars import BAR_TYPES
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/cli/progress_bars.py", line 9, in <module>
      from pip._internal.utils.logging import get_indentation
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/utils/logging.py", line 14, in <module>
      from pip._internal.utils.misc import ensure_dir
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/utils/misc.py", line 29, in <module>
      from pip._internal.locations import get_major_minor_version, site_packages, user_site
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/locations/__init__.py", line 9, in <module>
      from . import _distutils, _sysconfig
    File "/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/locations/_sysconfig.py", line 8, in <module>
      from pip._internal.exceptions import InvalidSchemeCombination, UserInstallationInvalid
  ImportError: cannot import name 'InvalidSchemeCombination' from 'pip._internal.exceptions' (/opt/hostedtoolcache/Python/3.7.9/x64/lib/python3.7/site-packages/pip/_internal/exceptions.py)
Error: The process '/opt/hostedtoolcache/Python/3.7.9/x64/bin/pip' failed with exit code 1

For macOS X，这个问题发生在我升级自制程序后， 真正对我有用的是这个

curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py

then

python get-pip.py

根据参考文献中的讨论，似乎只有pip version 21.1.1解决了问题。

参考下面的讨论https://github.com/pypa/pip/issues/7217 https://github.com/pypa/pip/issues/7217