During logout testing there were times where the logout would fail because the SP sent a logout request for a session that the IdP did not know about.

This was generally reproducable by doing this:

log in to SP A
hit secured page of SP B, should be logged-in automaticallyu

logout of B
A should be logged out as well

Log back into A
hit B again, logged in no auth

Log out of A
Fail

It is unclear whether this is an issue with the IdP or with mod_auth_mellon. It seemed like the SP was losing the new login session id though. When it would fail and I was attached to the SP using gdb and I watched as logout compared sessions, the session on the SP side had an identifier I'd never seen before.

This issue ticket was originally removed from the tracker as it clashed with the pull request.
See upstream ticket for migration details.