Comment 5 for bug 1292022

Horizon Neutron API interface already proposes a mechanism to cache and check if an extension is supported by the Neutron API [1].
I think we should add that test for the L3 extension.
And I also found another extension not tested: agent extension. That extension is used in the admin dashboard to list Neutron agents [2]. If that extension is not supported, Horizon raised a 404 error.

I think we need to check if a Neutron API request is dependent to an extension.
Perhaps, add a decorator to add that check?

[1] https://github.com/openstack/horizon/blob/master/openstack_dashboard/api/neutron.py#L831
[2] https://github.com/openstack/horizon/blob/master/openstack_dashboard/dashboards/admin/info/tables.py#L128