Backslash filenames in repo

[scop]

Missed in the review and already merged, but I think this is a filename that will cause problems e.g. on Windows, and it would be better created dynamically.

Originally posted by @scop in #1485

I'd like this addressed before releasing 2.17.0.

See also #1489

[akinomyoga]

I'd like this addressed before releasing 2.17.0.

I submitted the fix in #1491.

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There was a similar case:

By the way, it just occurred to me that this filename in the repo and tarballs will likely cause problems on Windows. We may want/need to create it on the fly, similarly as in test_unit_compgen_filedir.py's non_windows_testdir.

Originally posted by @scop in #1397 (comment)

This was fixed in #1408