[OVS] Exception message when retrieving bridge-id and is not present

In the OVS agent, when setting up the ancillary bridges, the parameter
external_id:bridge-id is retrieved. If this parameter is not defined
(e.g.: manually created bridges), ovsdbapp writes an error in the logs.
This information is irrelevant and can cause confusion during debugging time.

Change-Id: Ic85db65f651eb67fcb56b937ebe5850ec1e8f29f
Closes-Bug: #1815912

neutron/agent/common/ovs_lib.py

@@ -160,8 +160,10 @@ class BaseOVS(object):
     def get_bridges(self):
         return self.ovsdb.list_br().execute(check_error=True)
 
-    def get_bridge_external_bridge_id(self, bridge):
-        return self.ovsdb.br_get_external_id(bridge, 'bridge-id').execute()
+    def get_bridge_external_bridge_id(self, bridge, check_error=False,
+                                      log_errors=True):
+        return self.ovsdb.br_get_external_id(bridge, 'bridge-id').execute(
+            check_error=check_error, log_errors=log_errors)
 
     def set_db_attribute(self, table_name, record, column, value,
                          check_error=False, log_errors=True):

neutron/plugins/ml2/drivers/openvswitch/agent/ovs_neutron_agent.py

@@ -1082,7 +1082,8 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
         # bridge-id's configured
         br_names = []
         for bridge in ovs_bridges:
-            bridge_id = ovs.get_bridge_external_bridge_id(bridge)
+            bridge_id = ovs.get_bridge_external_bridge_id(bridge,
+                                                          log_errors=False)
             if bridge_id != bridge:
                 br_names.append(bridge)
         ovs_bridges.difference_update(br_names)

neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_neutron_agent.py

@@ -2435,7 +2435,7 @@ class AncillaryBridgesTest(object):
     def _test_ancillary_bridges(self, bridges, ancillary):
         device_ids = ancillary[:]
 
-        def pullup_side_effect(*args):
+        def pullup_side_effect(*args, **kwargs):
             # Check that the device_id exists, if it does return it
             # if it does not return None
             try:

neutron/tests/unit/plugins/ml2/drivers/openvswitch/agent/test_ovs_tunnel.py

@@ -186,7 +186,8 @@ class TunnelTest(object):
             ovs_lib.BaseOVS,
             'get_bridge_external_bridge_id').start()
         self.get_bridge_external_bridge_id.side_effect = (
-            lambda bridge: bridge if bridge in self.ovs_bridges else None)
+            lambda bridge, log_errors: bridge if bridge in self.ovs_bridges
+            else None)
 
         self.execute = mock.patch('neutron.agent.common.utils.execute').start()
         self.mock_check_bridge_datapath_id = mock.patch.object(