Comment 1 for bug 1983394

Looking at the test code [0], it looks like glance throws a different error than what the test expects as reason for not to be able to delete the namespace. I think this may also be a case of incorrect keystone policy.

[0] https://github.com/openstack/glance-tempest-plugin/blob/0.4.0/glance_tempest_plugin/tests/rbac/v2/metadefs/test_namespaces.py#L229