Tests fail with libxml-2.9.1

I'm finding that tests are failing on a fresh clone:
```
$ git clone django-compressor/django-compressor
$ cd django-compressor
$ mkvirtualenv compressor
$ workon compressor
$ pip install tox
$ tox -e py27-1.5.X
py27-1.5.X create: /home/aron/src/pp/django-compressor/.tox/py27-1.5.X
py27-1.5.X installdeps: Django>=1.5,<1.6, django-discover-runner, flake8, coverage, html5lib, mock, jinja2, lxml, BeautifulSoup, unittest2
py27-1.5.X develop-inst: /home/aron/src/pp/django-compressor
py27-1.5.X runtests: PYTHONHASHSEED='101664193'
py27-1.5.X runtests: commands[0] | django-admin.py --version
1.5.5
py27-1.5.X runtests: commands[1] | make test
flake8 compressor --ignore=E501,E128,E701,E261,E301,E126,E127
coverage run --branch --source=compressor `which django-admin.py` test --settings=compressor.test_settings compressor
Creating test database for alias 'default'...
..................................................................................................................................................................F.F......F.F...............................................................
======================================================================
FAIL: test_css_return_if_off (compressor.tests.test_parsers.LxmlParserTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/aron/src/pp/django-compressor/compressor/tests/test_base.py", line 107, in test_css_return_if_off
    self.assertEqual(self.css, self.css_node.output())
AssertionError: u'<link rel="stylesheet" href="/static/css/one.css" type="text/css" />\n<style t [truncated]... != u'<link rel="stylesheet" href="/static/css/one.css" type="text/css" />\n\n<style [truncated]...
  <link rel="stylesheet" href="/static/css/one.css" type="text/css" />
+ 
  <style type="text/css">p { border:5px solid green;}</style>
+ 
  <link rel="stylesheet" href="/static/css/two.css" type="text/css" />

======================================================================
FAIL: test_css_split (compressor.tests.test_parsers.LxmlParserTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/aron/src/pp/django-compressor/compressor/tests/test_base.py", line 88, in test_css_split
    self.assertEqual(out, split)
AssertionError: Lists differ: [(u'file', u'/home/aron/src/pp... != [(u'file', u'/home/aron/src/pp...

First differing element 0:
(u'file', u'/home/aron/src/pp/django-compressor/compressor/tests/static/css/one.css', u'css/one.css', u'<link rel="stylesheet" href="/static/css/one.css" type="text/css" />')
(u'file', u'/home/aron/src/pp/django-compressor/compressor/tests/static/css/one.css', u'css/one.css', u'<link rel="stylesheet" href="/static/css/one.css" type="text/css" />\n')

Diff is 811 characters long. Set self.maxDiff to None to see it.

======================================================================
FAIL: test_js_return_if_off (compressor.tests.test_parsers.LxmlParserTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/aron/src/pp/django-compressor/.tox/py27-1.5.X/lib/python2.7/site-packages/django/test/utils.py", line 224, in inner
    return test_func(*args, **kwargs)
  File "/home/aron/src/pp/django-compressor/compressor/tests/test_base.py", line 157, in test_js_return_if_off
    self.assertEqual(self.js, self.js_node.output())
AssertionError: u'<script src="/static/js/one.js" type="text/javascript"></script>\n<script type [truncated]... != u'<script src="/static/js/one.js" type="text/javascript"></script>\n\n<script ty [truncated]...
  <script src="/static/js/one.js" type="text/javascript"></script>
+ 
  <script type="text/javascript">obj.value = "value";</script>

======================================================================
FAIL: test_js_split (compressor.tests.test_parsers.LxmlParserTests)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/aron/src/pp/django-compressor/compressor/tests/test_base.py", line 135, in test_js_split
    self.assertEqual(out, split)
AssertionError: Lists differ: [(u'file', u'/home/aron/src/pp... != [(u'file', u'/home/aron/src/pp...

First differing element 0:
(u'file', u'/home/aron/src/pp/django-compressor/compressor/tests/static/js/one.js', u'js/one.js', u'<script src="/static/js/one.js" type="text/javascript"></script>')
(u'file', u'/home/aron/src/pp/django-compressor/compressor/tests/static/js/one.js', u'js/one.js', u'<script src="/static/js/one.js" type="text/javascript"></script>\n')

  [(u'file',
    u'/home/aron/src/pp/django-compressor/compressor/tests/static/js/one.js',
    u'js/one.js',
-   u'<script src="/static/js/one.js" type="text/javascript"></script>'),
+   u'<script src="/static/js/one.js" type="text/javascript"></script>\n'),
?                                                                     ++

   (u'inline',
    u'obj.value = "value";',
    None,
    u'<script type="text/javascript">obj.value = "value";</script>')]

----------------------------------------------------------------------
Ran 237 tests in 1.255s

FAILED (failures=4)
Destroying test database for alias 'default'...
make: *** [test] Error 1
ERROR: InvocationError: '/usr/bin/make test'
_________________________________________________________ summary __________________________________________________________
ERROR:   py27-1.5.X: commands failed
```