l2 gateway related ut failure

[YAMAMOTO Takashi]

eg.
http://logs.openstack.org/40/351040/1/check/gate-networking-midonet-python27-ubuntu-xenial/0e374ee/testr_results.html.gz

ft14.14: midonet.neutron.tests.unit.test_extension_l2gateway.MidonetL2GatewayTestCase.test_delete_midonet_l2gateway_connection_without_seg_id_StringException: Empty attachments:
  stderr
  stdout

pythonlogging:'': {{{
WARNING [stevedore.named] Could not load midonet.neutron.plugin_v2.MidonetPluginV2
 WARNING [stevedore.named] Could not load midonet.neutron.services.l2gateway.service_drivers.l2gw_midonet.MidonetL2gwDriver
 WARNING [neutron.api.extensions] Extension address-scope not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension auto-allocated-topology not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension availability_zone not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension default-subnetpools not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension dns-integration not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension dvr not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension flavors not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension ip_allocation not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension l2_adjacency not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension l3-ha not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension l3-flavors not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension l3_agent_scheduler not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension metering not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension multi-provider not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension net-mtu not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension network_availability_zone not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension network-ip-availability not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension qos not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension revisions not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension router_availability_zone not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension router-service-type not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension segment not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension service-type not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension tag not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension timestamp_core not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension trunk not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension trunk-details not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension vlan-transparent not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension file l2gateway.py wasn't loaded due to u'Validator type l2gwdevice_list is already defined'
 WARNING [neutron.api.extensions] Extension bgp-speaker-router-insertion not supported by any of loaded plugins
 WARNING [neutron.api.extensions] Extension logging-resource not supported by any of loaded plugins
   ERROR [neutron.api.extensions] Extension path 'neutron/tests/unit/extensions' doesn't exist!
}}}

Traceback (most recent call last):
  File "midonet/neutron/tests/unit/test_extension_l2gateway.py", line 78, in setUp
    service_plugins=service_plugins, ext_mgr=l2_gw_mgr)
  File "midonet/neutron/tests/unit/test_midonet_plugin_v2.py", line 105, in setUp
    self.setup_parent(service_plugins=service_plugins, ext_mgr=ext_mgr)
  File "midonet/neutron/tests/unit/test_midonet_plugin_v2.py", line 102, in setup_parent
    MidonetPluginConf.setUp(self, parent_setup)
  File "midonet/neutron/tests/unit/test_midonet_plugin_v2.py", line 75, in setUp
    parent_setup()
  File "/tmp/openstack/neutron/neutron/tests/unit/db/test_db_base_plugin_v2.py", line 131, in setUp
    self.api = router.APIRouter()
  File "/tmp/openstack/neutron/neutron/api/v2/router.py", line 76, in __init__
    ext_mgr = extensions.PluginAwareExtensionManager.get_instance()
  File "/tmp/openstack/neutron/neutron/api/extensions.py", line 657, in get_instance
    service_plugins)
  File "/tmp/openstack/neutron/neutron/api/extensions.py", line 616, in __init__
    self.check_if_plugin_extensions_loaded()
  File "/tmp/openstack/neutron/neutron/api/extensions.py", line 698, in check_if_plugin_extensions_loaded
    extensions=list(missing_aliases))
neutron.common.exceptions.ExtensionsNotFound: Extensions not found: ['l2-gateway'].

[YAMAMOTO Takashi (yamamoto)]

problematic change in l2gw repo seems reverted