OSPF key expire rules violates RFC 2293?

[Kenth Eriksson]

Hi!

When an OSPF key lifetime expires then bird stops using that key. E.g.
if the configured parameter "generate from time" expires, then bird
reverts to an OSPF interface in unauthenticated mode. 

Is this intentional? Or is it something that can be configured? I think
it is not according to the RFC. In appendix D of RFC 2293, the
following is stated;

"In the event that the last key associated with an interface expires,
it is unacceptable to revert to an unauthenticated condition, and not
advisable to disrupt routing."

Thanks,
Kenth