Don't use dict.iterkeys()

Iterating on a dictionary iterators on its keys, so calling its
iterkeys() method is not needed.

Moreover, the dict.iterkeys() method is gone in Python 3. This change
makes the modified code compatible with Python 3.

Blueprint nova-python3
Change-Id: I140f499d2054bb7d5486e4c61a2f886be6649cbb

nova/db/sqlalchemy/api.py

@@ -2158,7 +2158,7 @@ def _regex_instance_filter(query, filters):
 
     model = models.Instance
     db_regexp_op = _get_regexp_op_for_connection(CONF.database.connection)
-    for filter_name in filters.iterkeys():
+    for filter_name in filters:
         try:
             column_attr = getattr(model, filter_name)
         except AttributeError:

nova/test.py

@@ -292,8 +292,8 @@ class TestCase(testtools.TestCase):
         def inner(expected, observed):
             if isinstance(expected, dict) and isinstance(observed, dict):
                 self.assertEqual(len(expected), len(observed))
-                expected_keys = sorted(expected.iterkeys())
-                observed_keys = sorted(expected.iterkeys())
+                expected_keys = sorted(expected)
+                observed_keys = sorted(expected)
                 self.assertEqual(expected_keys, observed_keys)
 
                 expected_values_iter = iter(sort(expected.values()))

nova/tests/functional/test_servers.py

@@ -465,7 +465,7 @@ class ServersTest(ServersTestBase):
 
         # Cleanup
         self._delete_server(created_server_id)
-        for server_id in server_map.iterkeys():
+        for server_id in server_map:
             self._delete_server(server_id)
 
     def test_create_server_with_injected_files(self):

nova/tests/unit/api/openstack/compute/contrib/test_networks.py

@@ -223,7 +223,7 @@ class FakeNetworkAPI(object):
             net['broadcast'] = str(subnet_v4.broadcast)
             net['dhcp_start'] = str(subnet_v4[2])
 
-            for key in FAKE_NETWORKS[0].iterkeys():
+            for key in FAKE_NETWORKS[0]:
                 net.setdefault(key, kwargs.get(key))
             new_networks.append(net)
         self.networks += new_networks

tools/colorizer.py

@@ -268,7 +268,7 @@ class NovaTestResult(testtools.TestResult):
         self.stopTestRun()
 
     def stopTestRun(self):
-        for cls in list(self.results.iterkeys()):
+        for cls in list(self.results):
             self.writeTestCase(cls)
         self.stream.writeln()
         self.writeSlowTests()