Add setup_privsep in agent's main function

As Neutron switched to use pyroute2 for managing namespaces in
4f627b4e8dfe699944a196fe90e0642cced6278f
neutron-lbaas needs to setup privsep in agent to make
possible manipulating with network namespaces.

Change-Id: I084f8d54cc619a1c99658396d5cab036a2663413
Closes-Bug: #1723856

neutron_lbaas/agent/agent.py

@@ -57,6 +57,7 @@ def main():
 
     common_config.init(sys.argv[1:])
     config.setup_logging()
+    config.setup_privsep()
 
     mgr = manager.LbaasAgentManager(cfg.CONF)
     svc = LbaasAgentService(

neutron_lbaas/tests/unit/agent/test_agent.py

@@ -35,7 +35,9 @@ class TestLbaasService(base.BaseTestCase):
 
     def test_main(self):
         logging_str = 'neutron.conf.agent.common.setup_logging'
+        privsep_str = 'neutron.conf.agent.common.setup_privsep'
         with mock.patch(logging_str), \
+                mock.patch(privsep_str), \
                 mock.patch.object(agent.service, 'launch') as mock_launch, \
                 mock.patch('sys.argv'), \
                 mock.patch.object(agent.manager, 'LbaasAgentManager'), \