So in the unit test run using: $ tox -vvv -e py27 -- -r glance.tests.unit.v1.test_registry_api.TestRegistryAPI.test_update_all_image_members

I see that it is trying to serialize an HTTPNoContent exception and I also see a warning that in oslo.serialization 3.0 this will raise a ValueError() instead of printing a warning.

Also see it here: http://logs.openstack.org/72/533872/6/check/openstack-tox-py27/4709e32/job-output.txt.gz#_2018-01-16_13_10_38_931593

<HTTPNoContent at 0x7fe744f7fe60 204 No Content>

  File "/usr/lib64/python2.7/runpy.py", line 174, in _run_module_as_main
    "__main__", fname, loader, pkg_name)
  File "/usr/lib64/python2.7/runpy.py", line 72, in _run_code
    exec code in run_globals
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/subunit/run.py", line 149, in <module>
    main()
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/subunit/run.py", line 145, in main
    stdout=stdout, exit=False)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/run.py", line 187, in __init__
    self.runTests()
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/run.py", line 221, in runTests
    self.result = testRunner.run(self.test)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/subunit/run.py", line 70, in run
    test(result)
  File "/usr/lib64/python2.7/unittest/suite.py", line 70, in __call__
    return self.run(*args, **kwds)
  File "/usr/lib64/python2.7/unittest/suite.py", line 108, in run
    test(result)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/suite.py", line 87, in __call__
    return self.run(*args, **kwds)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/suite.py", line 126, in run
    test(result)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/suite.py", line 87, in __call__
    return self.run(*args, **kwds)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/suite.py", line 126, in run
    test(result)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/suite.py", line 87, in __call__
    return self.run(*args, **kwds)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/suite.py", line 126, in run
    test(result)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/unittest2/case.py", line 673, in __call__
    return self.run(*args, **kwds)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 671, in run
    return run_test.run(result)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/runtest.py", line 80, in run
    return self._run_one(actual_result)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/runtest.py", line 94, in _run_one
    return self._run_prepared_result(ExtendedToOriginalDecorator(result))
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/runtest.py", line 108, in _run_prepared_result
    self._run_core()
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/runtest.py", line 144, in _run_core
    self.case._run_test_method, self.result):
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/runtest.py", line 191, in _run_user
    return fn(*args, **kwargs)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/testtools/testcase.py", line 719, in _run_test_method
    return self._get_test_method()()
  File "glance/tests/unit/v1/test_registry_api.py", line 1645, in test_update_all_image_members_bad_request
    req.get_response(self.api)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/request.py", line 1327, in send
    application, catch_exc_info=False)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/request.py", line 1291, in call_application
    app_iter = application(self.environ, start_response)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/dec.py", line 131, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/dec.py", line 196, in call_func
    return self.func(req, *args, **kwargs)
  File "glance/common/wsgi.py", line 804, in __call__
    response = req.get_response(self.application)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/request.py", line 1327, in send
    application, catch_exc_info=False)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/request.py", line 1291, in call_application
    app_iter = application(self.environ, start_response)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/dec.py", line 145, in __call__
    return resp(environ, start_response)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/routes/middleware.py", line 141, in __call__
    response = self.app(environ, start_response)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/dec.py", line 145, in __call__
    return resp(environ, start_response)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/dec.py", line 131, in __call__
    resp = self.call_func(req, *args, **self.kwargs)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/webob/dec.py", line 196, in call_func
    return self.func(req, *args, **kwargs)
  File "glance/common/wsgi.py", line 1240, in __call__
    self.dispatch(self.serializer, action, response, action_result)
  File "glance/common/wsgi.py", line 1261, in dispatch
    return method(*args, **kwargs)
  File "glance/common/wsgi.py", line 1152, in default
    body = self.to_json(result)
  File "glance/common/wsgi.py", line 1148, in to_json
    return jsonutils.dump_as_bytes(data, default=self._sanitizer)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/oslo_serialization/jsonutils.py", line 233, in dump_as_bytes
    serialized = dumps(obj, default=default, **kwargs)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/oslo_serialization/jsonutils.py", line 217, in dumps
    return json.dumps(obj, default=default, **kwargs)
  File "/usr/lib64/python2.7/json/__init__.py", line 251, in dumps
    sort_keys=sort_keys, **kw).encode(obj)
  File "/usr/lib64/python2.7/json/encoder.py", line 207, in encode
    chunks = self.iterencode(o, _one_shot=True)
  File "/usr/lib64/python2.7/json/encoder.py", line 270, in iterencode
    return _iterencode(o, 0)
  File "glance/common/wsgi.py", line 1145, in _sanitizer
    return jsonutils.to_primitive(obj)
  File "/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/oslo_serialization/jsonutils.py", line 139, in to_primitive
    traceback.print_stack()
/home/devstack/openstack/glance/.tox/py27/lib/python2.7/site-packages/oslo_serialization/jsonutils.py:196: UserWarning: Cannot convert <HTTPNoContent at 0x7fe744f7fe60 204 No Content> to primitive, will raise ValueError instead of warning in version 3.0
  "instead of warning in version 3.0" % (value,))