how enforce an updated policy in /etc/nova/policy.json

>>> policy.enforce(nc,'quotas:update',{'getall':None})
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/lib/python2.7/dist-packages/nova/policy.py", line 92, in enforce
    init()
  File "/usr/lib/python2.7/dist-packages/nova/policy.py", line 62, in init
    reload_func=_set_rules)
  File "/usr/lib/python2.7/dist-packages/nova/utils.py", line 661, in read_cached_file
    mtime = os.path.getmtime(filename)
  File "/usr/lib/python2.7/genericpath.py", line 54, in getmtime
    return os.stat(filename).st_mtime
OSError: [Errno 2] No such file or directory: 'policy.json'

dir(policy)
['CONF', 'IsAdminCheck', '_', '_POLICY_CACHE', '_POLICY_PATH', '__builtins__', '__doc__', '__file__', '__name__', '__package__', '_set_rules', 'cfg', 'check_is_admin', 'enforce', 'exception', 'get_rules', 'init', 'os', 'policy', 'policy_opts', 'reset', 'utils']

got error in ice version python 2.7

dir(policy_engine) [‘class’, ‘delattr’, ‘doc’, ‘format’, ‘getattribute’, ‘hash’, ‘init’, ‘new’, ‘reduce’, ‘reduce_ex’, ‘repr’, ‘setattr’, ‘sizeof’, ‘str’, ‘subclasshook’]

https://review.openstack.org/gitweb?p=openstack/oslo-specs.git;a=commitdiff;h=17dc70a10053bd4231030c0ed5d9b0a377402b02

server_policies = [("compute_extension:quotas:update", ""),]

policy_engine = policy.get_rules()
policy_engine.register_opts(server_policies)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'register_opts'
>>> policy_engine.enforce('compute_extension:quotas:update', target, nc)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'enforce'