Fix compatibility with novaclient 7.0.0

Recent update of upper-constraints for novaclient 7.0.0 in [1]
breaked magnum.
This patch makes magnum code compatible with latest release.

Also, passed endpoint_override while class Initialization to
remove warning [2]:-

[1] https://review.openstack.org/#/c/414170/

[2] Property `management_url` is deprecated for SessionClient.
It should be set via `endpoint_override` variable while class
initialization.

Change-Id: Idc0e501c23b77ed5b4e9e9e7a6a7b6af7c7bca75
Closes-Bug: #1658058
Closes-Bug: #1658005

magnum/common/clients.py

@@ -165,9 +165,10 @@ class OpenStackClients(object):
             'insecure': self._get_client_option('nova', 'insecure')
         }
 
+        session = self.keystone().session
         self._nova = novaclient.Client(novaclient_version,
-                                       auth_token=self.auth_token, **args)
-        self._nova.client.management_url = endpoint
+                                       session=session,
+                                       endpoint_override=endpoint, **args)
         return self._nova
 
     @exception.wrap_keystone_exception

magnum/tests/unit/common/test_clients.py

@@ -232,21 +232,27 @@ class ClientsTest(base.BaseTestCase):
         self.assertEqual(barbican, barbican_cached)
 
     @mock.patch.object(novaclient, 'Client')
+    @mock.patch.object(clients.OpenStackClients, 'keystone')
     @mock.patch.object(clients.OpenStackClients, 'url_for')
     @mock.patch.object(clients.OpenStackClients, 'auth_url')
     def _test_clients_nova(self, expected_region_name, mock_auth, mock_url,
-                           mock_call):
+                           mock_keystone, mock_call):
         mock_auth.__get__ = mock.Mock(return_value="keystone_url")
         con = mock.MagicMock()
-        con.auth_token = "3bcc3d3a03f44e3d8377f9247b0ad155"
+        keystone = mock.MagicMock()
+        keystone.session = mock.MagicMock()
+        mock_keystone.return_value = keystone
         con.auth_url = "keystone_url"
         mock_url.return_value = "url_from_keystone"
         obj = clients.OpenStackClients(con)
         obj._nova = None
         obj.nova()
+        expected_kwargs = {'session': keystone.session,
+                           'endpoint_override': mock_url.return_value,
+                           'cacert': None,
+                           'insecure': False}
         mock_call.assert_called_once_with(CONF.nova_client.api_version,
-                                          auth_token=con.auth_token,
-                                          cacert=None, insecure=False)
+                                          **expected_kwargs)
         mock_url.assert_called_once_with(service_type='compute',
                                          interface='publicURL',
                                          region_name=expected_region_name)