Um, this sucks because I think that that means it was introduced after 2.6.4 final.  Since it's a regression, marking as a blocker for 2.6.5 final, but in order to stay a blocker it has to be a really critical bug and I'll want to review the fix before it goes it (to make sure it doesn't break anything else).  Otherwise, I'll bump it down to deferred blocker and we can fix it for 2.6.6.