In the backports to fix the policy of the original change, Dmitry
noted that it was actually wrong, because we should have instead
raised NotAuthorized. Dmitry was absolutely correct, because in hind
sight I made the change trying to keep exactly the same behavior,
but the reality is this is a case where we should be explicit,
and tell the user they have done something forbidden.
This revert of the revert fixes that change.
Original Change: https://review.opendev.org/c/openstack/ironic/+/905038
Dmitry's Review Feedback: https://review.opendev.org/c/openstack/ironic/+/905088
Change-Id: I5727df00b8c4ae9495ed14b5cea1c0734b5f688d
4398c11a5f