Modify the prompt of update network

The name is not required, so data["name"] may be empty,
but the network.name_or_id must have a value

Change-Id: Iec8d204b7211e9f5c58dbf886dadccfa824c9262

openstack_dashboard/dashboards/project/networks/forms.py

@@ -57,7 +57,8 @@ class UpdateNetwork(forms.SelfHandlingForm):
             network = api.neutron.network_update(request,
                                                  self.initial['network_id'],
                                                  **params)
-            msg = _('Network %s was successfully updated.') % data['name']
+            msg = (_('Network %s was successfully updated.') %
+                   network.name_or_id)
             messages.success(request, msg)
             return network
         except Exception as e: