ovs: fix regression when vlan mapping is not already registered

Bug introduced by Ic3c147136549b17aea0fe78e930a41a5b33ab9d8, when a
VLAN mapping is not registered during a call to
update_network_segement, the function should return None.

Closes-Bug: #2009215
Signed-off-by: Sahid Orentino Ferdjaoui <sahid.ferdjaoui@industrialdiscipline.com>
Change-Id: I91f8e8bd18d9956216e5715c658dfb408a2cbf07

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

@@ -507,6 +507,9 @@ class OVSNeutronAgent(l2population_rpc.L2populationRpcCallBackTunnelMixin,
             LOG.warning("Can't update segmentation id on no uniq segment "
                         "for a network %s", network['id'])
             return
+        except vlanmanager.MappingNotFound:
+            LOG.debug("Mapping not found for network %s", network['id'])
+            return
 
         if segmentation_id_old is None:
             # The segmentation id did not changed.

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

@@ -2725,6 +2725,15 @@ class TestOvsNeutronAgent(object):
             self.agent._update_network_segmentation_id(network)
             mock_get.assert_not_called()
 
+    def test__update_network_segmentation_id_mapping_not_found(self):
+        network = {'id': 'my-net-uuid',
+                   'segments': [mock.ANY]}
+        with mock.patch.object(self.agent.vlan_manager,
+                               'get') as mock_get:
+            mock_get.side_effect = ValueError
+            self.assertIsNone(
+                self.agent._update_network_segmentation_id(network))
+
     def _test_treat_smartnic_port(self, vif_type):
         vm_uuid = "407a79e0-e0be-4b7d-92a6-513b2161011b"
         iface_id = "407a79e0-e0be-4b7d-92a6-513b2161011c"