Stack trace from plugin._get_subnet() to db_base get_subnet(

  File "/home/apostal/PycharmProjects/neutron-community/neutron/db/db_base_plugin_v2.py", line 1760, in _ipam_try_allocate_ip
    ipam_subnet = ipam_driver.get_subnet(ip['subnet_id'])
  File "/home/apostal/PycharmProjects/neutron-community/neutron/ipam/drivers/neutrondb_ipam/driver.py", line 389, in get_subnet
    return NeutronDbSubnet.load(subnet_id, self._context)
  File "/home/apostal/PycharmProjects/neutron-community/neutron/ipam/drivers/neutrondb_ipam/driver.py", line 104, in load
    neutron_subnet = cls._fetch_subnet(ctx, neutron_subnet_id)
  File "/home/apostal/PycharmProjects/neutron-community/neutron/ipam/drivers/neutrondb_ipam/driver.py", line 49, in _fetch_subnet
    return plugin._get_subnet(context, id)
  File "/home/apostal/PycharmProjects/neutron-community/neutron/plugins/opencontrail/contrail_plugin.py", line 328, in _get_subnet
    subnet = self._get_resource('subnet', context, subnet_id, fields)
  File "/home/apostal/PycharmProjects/neutron-community/neutron/plugins/opencontrail/contrail_plugin.py", line 199, in _get_resource
    res_type, 'READ')
  File "/home/apostal/PycharmProjects/neutron-community/neutron/plugins/opencontrail/contrail_plugin.py", line 105, in _request_backend
    response = self._relay_request(url_path, data=data)
  File "/home/apostal/PycharmProjects/neutron-community/neutron/plugins/opencontrail/contrail_plugin.py", line 96, in _relay_request
    url, data=data, headers={'Content-type': 'application/json'})
  File "/home/apostal/PycharmProjects/neutron-community/neutron/plugins/opencontrail/contrail_plugin.py", line 86, in _request_api_server
    return requests.post(url, data=data, headers=headers)
  File "/home/apostal/.venv2_test/lib/python2.7/site-packages/mock.py", line 955, in __call__
    return _mock_self._mock_call(*args, **kwargs)
  File "/home/apostal/.venv2_test/lib/python2.7/site-packages/mock.py", line 1018, in _mock_call
    ret_val = effect(*args, **kwargs)
  File "/home/apostal/PycharmProjects/neutron-community/neutron/tests/unit/plugins/opencontrail/test_contrail_plugin.py", line 140, in request
    obj = func(context, data['id'])
  File "/home/apostal/PycharmProjects/neutron-community/neutron/db/db_base_plugin_v2.py", line 1373, in get_subnet