Tests are failing with recent expat versions

[mweinelt]

With expat 2.4.6 we're seeing the following tests fail in jxmlease 1.0.3:

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ERROR: test_namespace_collapse (tests.test.XMLToObjTestCase)
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Traceback (most recent call last):
  File "/build/jxmlease-1.0.3/tests/test.py", line 524, in test_namespace_collapse
    rv = self.parse(xml, process_namespaces=True, namespaces=namespaces)
  File "/build/jxmlease-1.0.3/jxmlease/xmlparser.py", line 326, in parse
    return Parser(**kwargs)(xml_input)
  File "/build/jxmlease-1.0.3/jxmlease/xmlparser.py", line 303, in __call__
    self._parser.Parse(xml_input, True)
xml.parsers.expat.ExpatError: out of memory: line 1, column 0

======================================================================
ERROR: test_namespace_support (tests.test.XMLToObjTestCase)
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Traceback (most recent call last):
  File "/build/jxmlease-1.0.3/tests/test.py", line 491, in test_namespace_support
    rv = self.parse(xml, process_namespaces=True)
  File "/build/jxmlease-1.0.3/jxmlease/xmlparser.py", line 326, in parse
    return Parser(**kwargs)(xml_input)
  File "/build/jxmlease-1.0.3/jxmlease/xmlparser.py", line 303, in __call__
    self._parser.Parse(xml_input, True)
xml.parsers.expat.ExpatError: out of memory: line 1, column 0

----------------------------------------------------------------------
Ran 98 tests in 5.740s

FAILED (errors=2, skipped=8)