Automatic DB password hash scheme selection

[Kurt Fitzner]

Hi all, 

Is there a way to get dovecot to recognize arbitrary password hash
schemes when looking up a password in a database? I originally set up
with #default_pass_scheme = MD5, and I would like to migrate to SHA512. 

Seeing as the scheme is actually stored in the password column along
with the password in the format $_<scheme#>_$_<salt>_$_<passwordhash>_,
it seems to me that dovecot should be able to look at the scheme number
and simply do the right thing. If this is possible, then migrating
passwords over would be much easier, since people will still be able to
log in with their old MD5-hashed password and the changer can be set up
to hash with the new method. 

Is this possible currently? 
Thanks, 

 Kurt