The following 2 line program fails under Python 2.6rc1: 
Python 2.6b3 (r26b3:66303, Sep  8 2008, 13:45:13) [MSC v.1500 32 bit
(Intel)] on win32

as downloaded today (2008-09-13):

#---- start program ---
import urllib
fh = urllib.urlopen('http://bugs.python.org/')
#---- end program ---

with the messages:
Traceback (most recent call last):
  File "bug.py", line 2, in <module>
    fh = urllib.urlopen('http://bugs.python.org/')
  File "d:\Python26\lib\urllib.py", line 87, in urlopen
    return opener.open(url)
  File "d:\Python26\lib\urllib.py", line 203, in open
    return getattr(self, name)(url)
  File "d:\Python26\lib\urllib.py", line 285, in open_http
    import httplib
  File "d:\Python26\lib\httplib.py", line 72, in <module>
    from test.test_support import catch_warning
ImportError: No module named test.test_support

The program works fine on Python 2.5