Tests fail with latest lxml 4.7.1 due to extra newlines

[mauritsvanrees]

In issue #7 I said I would add a separate issue for this, but promptly forgot it.

The failures are in these three tests:

repoze.xmliter.tests.TestIterator.test_getHTMLSerializer_doctype_xhtml_serializes_to_xhtml
repoze.xmliter.tests.TestIterator.test_replace_doctype
repoze.xmliter.tests.TestIterator.test_replace_doctype_blank

Sample error, note the extra newlines at the end:

b'<!D[194 chars]>Hello, w&#246;rld!<img src="foo.png" /></body>\n</html>\n' != b'<!D[194 chars]>Hello, w&#246;rld!<img src="foo.png" /></body>\n</html>\n\n\n'

  File "/srv/python3.9/lib/python3.9/unittest/case.py", line 59, in testPartExecutor
    yield
  File "/srv/python3.9/lib/python3.9/unittest/case.py", line 592, in run
    self._callTestMethod(testMethod)
  File "/srv/python3.9/lib/python3.9/unittest/case.py", line 550, in _callTestMethod
    method()
  File "/home/jenkins/.buildout/eggs/cp39/repoze.xmliter-0.6-py3.9.egg/repoze/xmliter/tests.py", line 167, in test_replace_doctype
    self.assertEqual(
  File "/srv/python3.9/lib/python3.9/unittest/case.py", line 837, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/srv/python3.9/lib/python3.9/unittest/case.py", line 830, in _baseAssertEqual
    raise self.failureException(msg)

See this Plone Jenkins PR job.

Looks easy to fix at first glance, just strip the result, and I can make a PR. But let's get some reactions on the other more general issue first.

[tseaver]

@mauritsvanrees I would do the proposed fix ASAP, and push a 0.6.1 release.

[mauritsvanrees]

PR created: #9