[3/3]Replace six.iteritems() with .items()

1.As mentioned in [1], we should avoid using
six.iteritems to achieve iterators. We can
use dict.items instead, as it will return
iterators in PY3 as well. And dict.items/keys
will more readable. 2.In py2, the performance
about list should be negligible, see the link [2].
[1] https://wiki.openstack.org/wiki/Python3
[2] http://lists.openstack.org/pipermail/openstack-dev/2015-June/066391.html

The patch list:
    tests.

Partial-Implements: blueprint replace-iteritems-with-items

Change-Id: I2d09c1d06370fed9c7c116a9eedea929fa5b5dc2

nova/tests/fixtures.py

@@ -30,7 +30,6 @@ from oslo_config import cfg
 from oslo_db.sqlalchemy import enginefacade
 import oslo_messaging as messaging
 from oslo_messaging import conffixture as messaging_conffixture
-import six
 
 from nova.api.openstack.placement import deploy as placement_deploy
 from nova.compute import rpcapi as compute_rpcapi
@@ -657,7 +656,7 @@ class ConfPatcher(fixtures.Fixture):
 
     def setUp(self):
         super(ConfPatcher, self).setUp()
-        for k, v in six.iteritems(self.args):
+        for k, v in self.args.items():
             self.addCleanup(CONF.clear_override, k, self.group)
             CONF.set_override(k, v, self.group)
 

nova/tests/unit/policy_fixture.py

@@ -17,7 +17,6 @@ import os
 import fixtures
 from oslo_policy import policy as oslo_policy
 from oslo_serialization import jsonutils
-import six
 
 import nova.conf
 from nova.conf import paths
@@ -124,7 +123,7 @@ class RoleBasedPolicyFixture(RealPolicyFixture):
         self.add_missing_default_rules(policy)
 
         # Convert all actions to require specified role
-        for action, rule in six.iteritems(policy):
+        for action in policy:
             policy[action] = 'role:%s' % self.role
 
         self.policy_dir = self.useFixture(fixtures.TempDir())