Mogan project CI error

[Gao Zexu]

openstack-tox-py27 check task of Mogan project failed, detail:

ft1.2: mogan.tests.unit.api.test_hooks.TestContextHook.test_context_hook_public_api_StringException: Traceback (most recent call last):
  File "/home/zuul/src/git.openstack.org/openstack/mogan/.tox/py27/local/lib/python2.7/site-packages/mock/mock.py", line 1305, in patched
    return func(*args, **keywargs)
  File "mogan/tests/unit/api/test_hooks.py", line 117, in test_context_hook_public_api
    context_hook.before(reqstate)
  File "mogan/api/hooks.py", line 89, in before
    is_admin = policy.check('is_admin', creds, creds)
  File "mogan/common/policy.py", line 344, in check
    return enforcer.enforce(rule, target, creds, *args, **kwargs)
  File "/home/zuul/src/git.openstack.org/openstack/mogan/.tox/py27/local/lib/python2.7/site-packages/oslo_policy/policy.py", line 851, in enforce
    if isinstance(creds, context.RequestContext):
TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and types

ft1.3: mogan.tests.unit.api.test_hooks.TestContextHook.test_context_hook_StringException: Traceback (most recent call last):
  File "/home/zuul/src/git.openstack.org/openstack/mogan/.tox/py27/local/lib/python2.7/site-packages/mock/mock.py", line 1305, in patched
    return func(*args, **keywargs)
  File "mogan/tests/unit/api/test_hooks.py", line 99, in test_context_hook
    context_hook.before(reqstate)
  File "mogan/api/hooks.py", line 89, in before
    is_admin = policy.check('is_admin', creds, creds)
  File "mogan/common/policy.py", line 344, in check
    return enforcer.enforce(rule, target, creds, *args, **kwargs)
  File "/home/zuul/src/git.openstack.org/openstack/mogan/.tox/py27/local/lib/python2.7/site-packages/oslo_policy/policy.py", line 851, in enforce
    if isinstance(creds, context.RequestContext):
TypeError: isinstance() arg 2 must be a class, type, or tuple of classes and types

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/625772

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/625772
Committed: https://git.openstack.org/cgit/openstack/mogan/commit/?id=c801a3f8eafac719f27b8444db5f035eb49ee501
Submitter: Zuul
Branch: master

commit c801a3f8eafac719f27b8444db5f035eb49ee501
Author: zxgao <email address hidden>
Date: Tue Dec 18 11:01:05 2018 +0800

    Fix context hook unit test error.

    Change-Id: I8559b62c2b485d385626253cfcca4ecda2ecaa7f
    Closes-Bug: 1808900