$ python -m locale
Locale aliasing:

Locale defaults as determined by getdefaultlocale():
------------------------------------------------------------------------
Language:  en_US
Encoding:  UTF8
..

Locale settings after calling resetlocale():
------------------------------------------------------------------------
Traceback (most recent call last):
 ..

  File "Lib/locale.py", line 548, in resetlocale
    _setlocale(category, _build_localename(getdefaultlocale()))
locale.Error: unsupported locale setting


Apparently the problem is due to locale.getdefaultlocale() returning encoding as 'UTF8' while locale.setlocale() expects 'UTF-8'.