cc @serhiy-storchaka @eryksun

@eryksun: I modified the implementation to only get the user preferred locale once, in the constructor. Is it better?

I tested manually the change on FreeBSD: it works, LC_TIME is also "C" at Python startup.

FreeBSD has a "POSIX" locale, but it's not used when LC_ALL, LC_CTYPE and LANG environment variable at not set: LC_CTYPE is "C" in this case.

I merged my PR. Thanks @eryksun for your feedback and the nice idea of reusing with different_locale(""): to get the user preferred locale :-)

calendar should now be a little bit better in some corner cases, but for the regular use case, there should be no change between Python 3.10 and 3.11.