[Dovecot] ACLs: Group ACL adds empty ACL for user of same name, why?

[Jim Hague]

I'm playing around with ACLs, Groups and SOGo on Debian Stable, Dovecot 
1.2.15.

If I set an ACL for a group 'developers':

6 setacl "INBOX.Trash" "$developers" "lrsw"
6 OK Setacl complete.

The dovecot-acl file for INBOX.Trash then contains a group setting for the 
group, and a user setting for a user of the same name, giving it no 
permissions.

group=developers lrws
user=developers

and a subsequent GETACL reports the user:

5 getacl "INBOX.Trash"
* ACL "INBOX.Trash" "$developers" lrws "developers" "" "jim" lrwstipekxacd
5 OK Getacl completed.

Currently SOGo does not deal well with the unexpected non-existant user.
So I'm curious - why's it there? 
-- 
Jim Hague - jim.hague at acm.org          Never trust a computer you can't lift.