I'm getting what looks like a PEP 383-related failure in test_os, on OS 
X 10.5.6.  Here's the tail end of running Lib/test/test_os.py, on a
standard non-debug build of py3k.

test_setuid (__main__.PosixUidGidTests) ... ok
test_listdir (__main__.Pep383Tests) ... FAIL
test_open (__main__.Pep383Tests) ... ok
test_stat (__main__.Pep383Tests) ... ok

======================================================================
FAIL: test_listdir (__main__.Pep383Tests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "Lib/test/test_os.py", line 725, in test_listdir
    self.assertEquals(found, expected)
AssertionError: Items in the first set but not the second:
'fooöbar'
'foo%F6bar'
Items in the second set but not the first:
'foo\udcf6bar'
'fooöbar'

----------------------------------------------------------------------
Ran 60 tests in 0.079s

FAILED (failures=1)
Traceback (most recent call last):
  File "Lib/test/test_os.py", line 758, in <module>
    test_main()
  File "Lib/test/test_os.py", line 754, in test_main
    Pep383Tests
  File "/Users/dickinsm/svn/python/py3k/Lib/test/support.py", line 878, 
in run_unittest
    _run_suite(suite)
  File "/Users/dickinsm/svn/python/py3k/Lib/test/support.py", line 861, 
in _run_suite
    raise TestFailed(err)
test.support.TestFailed: Traceback (most recent call last):
  File "Lib/test/test_os.py", line 725, in test_listdir
    self.assertEquals(found, expected)
AssertionError: Items in the first set but not the second:
'fooöbar'
'foo%F6bar'
Items in the second set but not the first:
'foo\udcf6bar'
'fooöbar'