When kadmind performs a password change on behalf of a principal, it
stored kadmind@REALM in the mod_princ data instead of the original
principal that authenticated against kadmind.
This makes the mod_princ field much less useful as you cannot use it's
data to determine who actually performed the password change.
Also in the DAL the mod_princ data is the only way to know who operated
the password change in order to take decisions based on that datum.