Comment 3 for bug 413514

More details:

On jaunty:
LANG=BOGUS python2.6
Python 2.6.2 (release26-maint, Apr 19 2009, 01:58:18)
[GCC 4.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import bzrlib.osutils
bzr: warning: unsupported locale setting
  Could not determine what text encoding to use.
  This error usually means your Python interpreter
  doesn't support the locale set by $LANG (BOGUS)
  Continuing with ascii encoding.
>>> bzrlib.osutils.get_user_encoding()
'ascii'
>>>

On karmic:

LANG=BOGUS python2.6
Python 2.6.2+ (release26-maint, Jul 24 2009, 16:18:09)
[GCC 4.4.1] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import bzrlib.osutils
>>> bzrlib.osutils.get_user_encoding()
'ANSI_X3.4-1968'
>>>

Basically a change in python26, specific to karmic, makes python roughly behave as bzr regarding user_encoding: default to ascii (ANSI_X3.4-1968 being a funny name for ascii) but it stopped emitting warnings.