su is asking superuser for password

["Dennis Melentyev" <dennis.melentyev@xxxxxxxxx>]

Hi community,

After the last upgrade on Jan' 4th to:

dennis@dfly> uname -a
DragonFly dfly.melent.local 2.1.1-DEVELOPMENT DragonFly
2.1.1-DEVELOPMENT #1: Sun Jan  4 04:51:33 EET 2009
root@dfly.melent.local:/usr/obj/usr/src/sys/GENERIC  i386

su started asking for a password while su'ing from root to less
privileged users.

Steps to reproduce:
1. login as regular user
2. dennis@dfly> sudo su -
Password:
3. root@dfly# su bind
Password: <just enter>
pam_unix: pam_sm_authenticate: UNIX authentication refused
su: Sorry