[Dovecot] in a major jam... authentication

[tallison1]

I was upgrading my debian box and managed to upgrade my dovecot 
installation at the same time.  I wasn't planning on it, but it came 
along just the same.

I took some notes on what I thought I needed to change, but apparently 
it wasn't enough.

I've been running this for quite some time now with pgsql authentication 
and it's been one of those nice applications that always behave themselves.

Until now.

I can connect to the database.  But I always fail the authentication.
 From the logs I'm coming in on a PLAIN authentication and failing on 
"password mismatch"
The database hasn't changed the password in years.
The database stores the password as (I believe) an md5 encryption of the 
real password.  Whatever it is, it is definitely encrypted in the table.

What I had in my configuration file was something like this:
disable_plaintext_auth = no  (this was marked as the default and I 
enforced it in the new file)
auth_mechanisms = plain
auth_passdb = pgsql:/etc/dovecot/dovecot-pgsql.conf
auth_user = root
login = imap

I have updated the configuration as follows:
dovecot-pgsql.conf
'driver = pgsql'
'default_pass_scheme = PLAIN-MD5'
( I tried changing this to PLAIN but it didn't help )

dovecot.conf
protocols = imap
disable_plaintext_auth = no
protocol imap {
}
protocol pop3 {
}
auth default {
   mechanisms = plain
   passdb pam {
   }
   passdb sql {
     args = /etc/dovecot/dovecot-pgsql.conf
   }

   userdb passwd {
   }
   user = root
}

I'm not sure what to try now, all I know is that my IMAP server is just 
dead and I'm unable to get the authentication working again.  I can't 
find much that says how to set this up again and am reluctant to just 
start trying stuff.