dnspython 1.14.0 breaks py3x unit tests

[Graham Hayes]

dnspython 1.14.0 breaks py3x unit tests

see: https://github.com/rthalley/dnspython/issues/209

[Graham Hayes (grahamhayes)]

e.g. from http://logs.openstack.org/46/377746/1/check/gate-designate-python34-db/6263198/testr_results.html.gz:
    Traceback (most recent call last):
      File "/home/jenkins/workspace/gate-designate-python34-db/.tox/py34/lib/python3.4/site-packages/mock/mock.py", line 1305, in patched
        return func(*args, **keywargs)
      File "/home/jenkins/workspace/gate-designate-python34-db/designate/tests/test_agent/test_backends/test_denominator.py", line 82, in test_update_zone
        self.backend.update_zone(zone)
      File "/home/jenkins/workspace/gate-designate-python34-db/designate/backend/agent_backend/impl_denominator.py", line 185, in update_zone
        output = self.denominator.get_records(zone_name)
      File "/home/jenkins/workspace/gate-designate-python34-db/designate/backend/agent_backend/impl_denominator.py", line 54, in get_records
        return self._execute(['record', '-z', zone, 'list'], kwargs)
      File "/home/jenkins/workspace/gate-designate-python34-db/designate/backend/agent_backend/impl_denominator.py", line 81, in _execute
        LOG.debug(('Executing Denominator call: %s' % ' '.join(call)))
    TypeError: sequence item 8: expected str instance, bytes found

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/378653

[OpenStack Infra (hudson-openstack)]

Change abandoned by Kiall Mac Innes (<email address hidden>) on branch: master
Review: https://review.openstack.org/378653