Nbdev CI / Build fails on one of my imports

my library won’t build on github. the error is below.

Collecting enum
  Downloading enum-0.4.7.tar.gz (20 kB)
    ERROR: Command errored out with exit status 1:
     command: /opt/hostedtoolcache/Python/3.6.12/x64/bin/python -c 'import sys, setuptools, tokenize; sys.argv[0] = '"'"'/tmp/pip-install-6v2kfdec/enum/setup.py'"'"'; __file__='"'"'/tmp/pip-install-6v2kfdec/enum/setup.py'"'"';f=getattr(tokenize, '"'"'open'"'"', open)(__file__);code=f.read().replace('"'"'\r\n'"'"', '"'"'\n'"'"');f.close();exec(compile(code, __file__, '"'"'exec'"'"'))' egg_info --egg-base /tmp/pip-pip-egg-info-5ir2lltt
         cwd: /tmp/pip-install-6v2kfdec/enum/
    Complete output (11 lines):
    Traceback (most recent call last):
      File "<string>", line 1, in <module>
      File "/opt/hostedtoolcache/Python/3.6.12/x64/lib/python3.6/site-packages/setuptools/__init__.py", line 6, in <module>
        import distutils.core
      File "/opt/hostedtoolcache/Python/3.6.12/x64/lib/python3.6/distutils/core.py", line 16, in <module>
        from distutils.dist import Distribution
      File "/opt/hostedtoolcache/Python/3.6.12/x64/lib/python3.6/distutils/dist.py", line 9, in <module>
        import re
      File "/opt/hostedtoolcache/Python/3.6.12/x64/lib/python3.6/re.py", line 142, in <module>
        class RegexFlag(enum.IntFlag):
    AttributeError: module 'enum' has no attribute 'IntFlag'
ERROR: Command errored out with exit status 1: python setup.py egg_info Check the logs for full command output.
##[error]Process completed with exit code 1.

i’m not sure what i’m meant to do with this… :-/

I have no idea, but the python path looks awfully suspicious for something running inside GitHub Actions

part of the CI builds the library and setup packages etc so I believe that’s expected (although this is my first time playing with it).

It turns out this is nothing to do with nbdev.

I’d blindly added everything I import to my requirements in settings.ini including some standard lib stuff. There is however, a pypi package called enum (from before python had enum support) which blows up with this error when you try and pip install it.