disable sieve replication with dsync

[David Mandelberg]

Hi,

I think I got dsync working for mail, but I'm getting these errors:

Error: sieve: file storage: 
mkdir_parents_chgrp(/usr/local/etc/mail/mandelberg.org/david/sieve/tmp) 
failed: Read-only file system

I'm managing sieve files externally, and I don't want any part of 
dovecot writing to them. Is there any way to configure dsync to not 
replicate them? I looked at doveadm-sync(1) to see about adding a flag 
to replication_dsync_parameters, but the closest thing I see is -x for 
excluding mailboxes. Or maybe -o? Is there a way to specify a nested 
setting to -o, so I could do something like `plugin { sieve = }` for dsync?