[Dovecot] Dovecot auth user lookup patch for maildrop

[mr.maX]

>> +One significant difference compared to Courier Authlib extension is 
>> that Dovecot +Authentication extension will never return uid/gid  that's 
>> equal to zero.
>
> This isn't actually true always. gid=0 can be returned, although to  get 
> that working with imap/pop3 requires also setting  first_valid_gid=0. 
> uid=0 is never returned though.

I wasn't really talking about what Dovecot would return from its database. 
While speaking about "Dovecot Authentication extension" in my text I was 
refering to my extension to maildrop, which will simply refuse to operate 
(and cause maildrop to tempfail) if it somehow gets uid/gid that's equal to 
zero (or system user that's root) as an answer to the auth master query. If 
I'm not mistaken Dovecot's LDA deliver will also refuse to accept uid/gid 
that's zero and I based behavior of my maildrop extension on that.

--
Regards,
Marko Njezic