[Dovecot] cache_key assertion error 1.0.beta8

I just added auth caching with pam, and I'm getting this error:

dovecot: [ID 107833 mail.error] auth(default): file passdb.c: line 178 (passdb_init): assertion failed: (passdb->passdb->default_pass_scheme != NULL || passdb->passdb->cache_key == NULL)

A google search turns up http://www.dovecot.org/list/dovecot-cvs/2005-March/004117.html which looks approx like this except the assertion above is in passdb.c.

Anyway, is this a known problem in 1.0.beta8? I've been reluctant to upgrade to the rc's due to all the problems.

-frank