>> What does use getlocale is time.strptime and datetime.datetime.strptime, so when getlocale fails, strptime fails.

> Would they work with getlocale() returning None for the encoding ?

Yes. All getlocale is used for in _strptime.py is comparing the value returned to the previous value returned.

I expect changing _strptime._getlang to return the unnormalized value locale._setlocale(locale.LC_TIME, None) would work as well and more robustly.