> -            check('utf8=0', [arg.decode(encoding, 'surrogateescape')],
> +            check('utf8=0', [arg.decode('ascii', 'surrogateescape')],
>                    LC_ALL='C')
>  (...)
> == Tests result: SUCCESS ==

Good, it works.

I updated my PR 8969 to implement properly my idea. With this PR, on HP-UX with C or POSIX locale, Python now uses ASCII for its "filesystem encoding": sys.getfilesystemencoding() returns "ascii".

Michael: can you please try my updated PR 8969?

* apply the updated change
* recompile Python
* run the test suite using: LC_ALL=C ./python -m test -j0 -r

You may also test with the current locale: ./python -m test -j0 -r

If everything is good on your side, I will merge my PR.