[Dovecot] dsync error Mailbox has children, delete them first

Hi,

I use dsync to backup mailboxes from mbox format to mdbox on a remote
system. The first run for a user with dsync is OK, but during the
second there are lots of the following errors:

dsync-remote(user): Error: Can't delete mailbox directory Example:
Mailbox has children, delete them first

I see no way how I could influence the order dsync deletes mailboxes.
This happens with dovecot version 2.0.16

Thank you, Juergen Obermann