STINNER Victor wrote:
> 
> STINNER Victor <victor.stinner@haypocalc.com> added the comment:
> 
> Here you have a patch. It adds tests in test_sys.
> 
> The tests are skipped on a non-ascii Python executable path because of #8611 (see #9425).

Thanks for the patch.

A couple of notes:

 * The command line -h explanation is missing from the patch.

 * The documentation should mention that the env var is only
   read once; subsequent changes to the env var are not seen
   by Python

 * If the codec lookup fails, Python should either issue a warning
   and then ignore the env var (using the get_codeset() API).

 * Unrelated to the env var, but still important: if get_codeset()
   does not return a known codec, Python should issue a warning
   before falling back to the default setting. Otherwise, a
   Python user will never know that there's an issue and this
   make debugging a lot harder.

We should also add a new sys.setfilesystemencoding()
function to make changes possible after Python startup. This
would have to go on a separate ticket, though. Or is there
some concept preventing this ?