That's a very good point. As it is now, in the update functions (update network, router and port) the Neutron API is called first, and it will throw an exception if the resource doesn't exist. However, it may be the case, as it was until this patch with admin_state_up, that through the Neutron API a user updates a field that we don't support; then we would be fetching a resource and to do nothing with it. That's what the Lazy proxy is mostly avoiding.

Either way, I'll update the code with a comment making that behaviour explicit.