[Twisted-Python] Test failure in with Python 2.2

[Andrew Bennetts]

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FAIL: testFileRebuild (twisted.test.test_rebuild.RebuildTestCase)
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Traceback (most recent call last):
  File "./twisted/test/test_rebuild.py", line 73, in testFileRebuild
    assert b.b() == 'c'
AssertionError
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I presume this is an issue with the special new-style class support...

-Andrew.