One example:

http://buildbot.python.org/all/builders/PPC64%20AIX%203.x/builds/957/steps/test/logs/stdio

0:08:55 [ 91/406/2] test_c_locale_coercion failed -- running: test_importlib (41 sec)
skipped 'No C-with-UTF-8 locale available'
test_LC_ALL_set_to_C (test.test_c_locale_coercion.LocaleCoercionTests) ... test_PYTHONCOERCECLOCALE_not_zero (test.test_c_locale_coercion.LocaleCoercionTests) ... test_PYTHONCOERCECLOCALE_set_to_warn (test.test_c_locale_coercion.LocaleCoercionTests) ... test_PYTHONCOERCECLOCALE_set_to_zero (test.test_c_locale_coercion.LocaleCoercionTests) ... test_test_PYTHONCOERCECLOCALE_not_set (test.test_c_locale_coercion.LocaleCoercionTests) ... 
======================================================================
FAIL: test_LC_ALL_set_to_C (test.test_c_locale_coercion.LocaleCoercionTests) (env_var='LANG', nominal_locale='', PYTHONCOERCECLOCALE=None)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/shager/cpython-buildarea/3.x.edelsohn-aix-ppc64/build/Lib/test/test_c_locale_coercion.py", line 309, in _check_c_locale_coercion
    coercion_expected)
  File "/home/shager/cpython-buildarea/3.x.edelsohn-aix-ppc64/build/Lib/test/test_c_locale_coercion.py", line 202, in _check_child_encoding_details
    self.assertEqual(encoding_details, expected_details)
AssertionError: {'fsencoding': 'iso8859-1', 'stdin_info': 'iso8859-1:surr[140 chars] 'c'} != {'fsencoding': 'ascii', 'stdin_info': 'ascii:surrogateesc[124 chars] 'c'}
- {'fsencoding': 'iso8859-1',
?                  ^^^^^^^^

+ {'fsencoding': 'ascii',
?                 +++ ^

   'lang': '',
   'lc_all': 'c',
   'lc_ctype': '',
-  'stderr_info': 'iso8859-1:backslashreplace',
?                   ^^^^^^^^

+  'stderr_info': 'ascii:backslashreplace',
?                  +++ ^

-  'stdin_info': 'iso8859-1:surrogateescape',
?                  ^^^^^^^^

+  'stdin_info': 'ascii:surrogateescape',
?                 +++ ^

-  'stdout_info': 'iso8859-1:surrogateescape'}
?                   ^^^^^^^^

+  'stdout_info': 'ascii:surrogateescape'}
?                  +++ ^