py27 tox tests fail with a TypeError

[Ryan Petrello]

Currently, tests run via `tox -epy27` are failing with a TypeError:

An example of the full traceback of the failure can be found here:

Captured traceback:
~~~~~~~~~~~~~~~~~~~
    Traceback (most recent call last):
      File "designate/tests/unit/test_backend/test_designate.py", line 78, in setUp
        self.backend = impl_designate.DesignateBackend(self.target)
      File "designate/backend/impl_designate.py", line 42, in __init__
        super(DesignateBackend, self).__init__(target)
      File "designate/backend/base.py", line 49, in __init__
        self.admin_context = DesignateContext.get_admin_context()
      File "designate/context.py", line 138, in get_admin_context
        return cls(None, **kwargs)
      File "designate/context.py", line 45, in __init__
        super(DesignateContext, self).__init__(
    TypeError: must be type, not MagicMock

======
Totals
======
Ran: 1249 tests in 81.0000 sec.
 - Passed: 1238
 - Skipped: 3
 - Expected Fail: 4
 - Unexpected Success: 0
 - Failed: 4

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/272219

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/272219
Committed: https://git.openstack.org/cgit/openstack/designate/commit/?id=eba1f9e9b4e5f67b94fdb15192359d09bd0dba72
Submitter: Jenkins
Branch: master

commit eba1f9e9b4e5f67b94fdb15192359d09bd0dba72
Author: Kiall Mac Innes <email address hidden>
Date: Mon Jan 25 18:36:43 2016 +0000

    Ensure mocks are stopped after use

    When a mock is stated by hand, rather than used as a decorator
    or context manager, care must be take to stop the mock before
    the next test.

    Change-Id: Iceb1a4fc80d5e895a5644134e8e95f06c5421f47
    Partial-Bug: 1537851

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/liberty
Review: https://review.openstack.org/273723

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/273723
Committed: https://git.openstack.org/cgit/openstack/designate/commit/?id=67175e7a1928b281e6e94516fcd77874166cbb14
Submitter: Jenkins
Branch: stable/liberty

commit 67175e7a1928b281e6e94516fcd77874166cbb14
Author: Kiall Mac Innes <email address hidden>
Date: Mon Jan 25 18:36:43 2016 +0000

    Ensure mocks are stopped after use

    When a mock is stated by hand, rather than used as a decorator
    or context manager, care must be take to stop the mock before
    the next test.

    Change-Id: Iceb1a4fc80d5e895a5644134e8e95f06c5421f47
    Partial-Bug: 1537851
    (cherry picked from commit eba1f9e9b4e5f67b94fdb15192359d09bd0dba72)