fakeui service failed with AttributeError: 'module' object has no attribute 'add_metaclass'

Service installed by fakeui scripts (http://jenkins-product.srt.mirantis.net:8080/view/devops/job/fuelweb_fakeui/11886/console) fails.

From /var/log/nailgun.log:

2014-09-08 13:06:25.052 ERROR [7f8010ef4700] (settings) Error while reading config file /etc/nailgun/settings.yaml: [Errno 2] No such file or directory: '/etc/nailgun/settings.yaml'
Traceback (most recent call last):
  File "manage.py", line 269, in <module>
    action(params) if action else parser.print_help()
  File "manage.py", line 245, in action_run
    from nailgun.app import appstart
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/app.py", line 31, in <module>
    from nailgun.middleware.keystone import NailgunFakeKeystoneAuthMiddleware
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/middleware/keystone.py", line 19, in <module>
    from nailgun.api.v1 import urls as api_urls
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/api/v1/urls.py", line 22, in <module>
    from nailgun.api.v1.handlers.capacity import CapacityLogCsvHandler
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/api/v1/handlers/capacity.py", line 29, in <module>
    from nailgun.task.manager import GenerateCapacityLogTaskManager
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/task/manager.py", line 36, in <module>
    from nailgun.task import task as tasks
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/task/task.py", line 39, in <module>
    from nailgun.orchestrator import deployment_serializers
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/orchestrator/deployment_serializers.py", line 39, in <module>
    from nailgun.orchestrator import priority_serializers as ps
  File "/home/jenkins/workspace/fuelweb_fakeui/build/repos/nailgun/nailgun/nailgun/orchestrator/priority_serializers.py", line 74, in <module>
    @six.add_metaclass(abc.ABCMeta)
AttributeError: 'module' object has no attribute 'add_metaclass'