[Dovecot] Dsync fails on second sync for folders with dot in the name

I'm in the processes of running our first dsync backup of all users (from maildir to mdbox on remote server), and one problem I'm hitting that dsync will work fine on first run for some users, and then reliably fail whenever I try a new run:

$ sudo dsync -u janfrode@example.net backup ssh -q mailbackup@repo1.example.net dsync -u janfrode@example.net
$ sudo dsync -u janfrode@example.net backup ssh -q mailbackup@repo1.example.net dsync -u janfrode@example.net
dsync-remote(janfrode@example.net): Error: Can't delete mailbox directory INBOX/a: Mailbox has children, delete them first

The problem here seems to be that this user has a maildir named ".a.b". On the backup side I see this as "a/b/".

So dsync doesn't quite seem to agree with itself for how to handle folders with dot in the name.

-jf