[Dovecot] nopassword not working in Dovecot 2.2rc3?

Hello,

I got some problems while set up a test system for Client Cert Auth, therefore passwords are not requred.

SELECT NULL AS password, 'Y' as nopassword, userid AS user FROM users WHERE userid = 'user@example.net'

shows exactly what is expected, bur Dovecot does net regongnize 'Y' as nopassword:

Mar 25 11:18:04 dovecot dovecot: auth: Debug: sql(user@example.net,192.168.200.6,): query: SELECT NULL AS password, 'Y' as nopassword, userid AS user FROM users WHERE userid = 'user@example.net' Mar 25 11:18:04 dovecot dovecot: auth: sql(user@example.net,192.168.200.6,): Empty password returned without nopassword Mar 25 11:18:06 dovecot dovecot: auth: Debug: client passdb out: FAIL#0112#011user=user@example.net Mar 25 11:18:07 dovecot dovecot: imap-login: Disconnected (auth failed, 2 attempts in 9 secs): user=user@example.net, method=PLAIN, rip=192.168.200.6, lip=192.168.200.22, TLS

As shown on http://wiki2.dovecot.org/AuthDatabase/SQL select statement above should prevent Dovecot from verifying password.

any hints?

best regards Christian