flags need a separate backup outside of the ferret index

Ferret still occasionally barfs and corrupts its own index. Currently all user state is stored in the index and only in the index, so that means you lose big-time if that happens. You can sup-dump your labels, but really, how often are you going to do that. Sup should maintain a separate backup of all labels in some fast on-disk hashtable (message ids to label sets). Bdb comes to mind.