Seems at test for os.environ that uses mapping_tests.py to make 
sure the object returned by os.environ has a mapping 
environment is failing under 2.4 (fine under 2.5) at least on OS X:

test.test_support.TestFailed: Traceback (most recent call last):
  File "/Users/drifty/Code/cvs/Trees/python24/Lib/test/
mapping_tests.py", line 204, in test_update
    d.update(SimpleUserDict())
  File "/Users/drifty/Code/cvs/Trees/python24/Lib/os.py", line 467, 
in update
    for k, v in items:
  File "/Users/drifty/Code/cvs/Trees/python24/Lib/test/
mapping_tests.py", line 202, in __getitem__
    return self.d[i]
KeyError: 0