This looks like an interaction with test_distutils.  On OS X 10.5.6 I get:

Macintosh-4:py3k dickinsm$ ./python.exe Lib/test/regrtest.py test_distutils test_httpservers
test_distutils
test_httpservers
Traceback (most recent call last):
  File "/private/var/folders/nL/nLe5s1a2G807X4++Ih2+y++++TI/-Tmp-/tmpXvtrLE/cgi-bin/file2.py", line 2, in <module>
    import cgi
  File "/Users/dickinsm/svn/python/py3k/Lib/cgi.py", line 34, in <module>
    from operator import attrgetter
ImportError: No module named operator
test test_httpservers failed -- Traceback (most recent call last):
  File "/Users/dickinsm/svn/python/py3k/Lib/test/test_httpservers.py", line 370, in test_post
    self.assertEquals(res.read(), b'1, python, 123456\n')
AssertionError: b'' != b'1, python, 123456\n'

1 test OK.
1 test failed:
    test_httpservers

But if I run test_httpservers by itself all tests pass.

Adding Tarek to the nosy list, in case he knows anything that might help.