Fix intermittent test failure of test_fillmeldhtmlform on Python 3.3.
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FAIL: test_fillmeldhtmlform (meld3.test_meld3.MeldAPITests)
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Traceback (most recent call last):
  File "/path/to/meld3/meld3/test_meld3.py", line 424, in test_fillmeldhtmlform
    self.assertEqual(unfilled, ['notthere', 'suffix'])
AssertionError: Lists differ: ['suffix', 'notthere'] != ['notthere', 'suffix']

First differing element 0:
suffix
notthere

- ['suffix', 'notthere']
+ ['notthere', 'suffix']