Tests on Windows started failing since WSL was made available on GitHub Actions

[The-Compiler]

See e.g. https://github.com/pytest-dev/pytest/pull/7516/checks?check_run_id=889498913#step:7:172 from #7516.

That smells like a change in the GitHub Actions environments, as the error message reads (with a couple of NUL-bytes in between):

running: bash C:\Users\runneradmin\AppData\Local\Temp\pytest-of-runneradmin\pytest-0\popen-gw0\test_argcomplete0\test_argcomplete --fu
     in: C:\Users\runneradmin\AppData\Local\Temp\pytest-of-runneradmin\pytest-0\popen-gw0\test_argcomplete0
Windows Subsystem for Linux has no installed distributions.


Distributions can be installed by visiting the Microsoft Store:


https://aka.ms/wslstore

Probably due to this: actions/runner-images#1081.
Not sure what to do here. Should we just skip that test on Windows? Or perhaps if on Windows and on GitHub Actions?

[bluetech]

From the log it looks like bash is in PATH in Windows, but is not actually bash, but some wrapper script which fails...

Maybe in addition to the which we can also skip if bash --version fails, or some other safe check to verify this is actually bash.

[The-Compiler]

Yeah, I suppose something like running bash --version and checking that the output starts with GNU bash would be better. I won't have time to submit a PR right now I'm afraid, so feel free to go ahead if you have the time.