Updated openstack/openstack
Project: openstack/oslo.config  f56b38c3884ae921d9964b18af5f3ded4ab97e6f

Reject option names prefixed with '_'

Such names are used for _Namespace's internal purposes.

Change-Id: I08c24f05ec3ef626b253ca3682439c1a162959e5
Related-Bug: #1284969