[Dovecot] Sharing user folders doesn't work when users have periods in names.

I am using period as an IMAP separator with Maildir directories and I cannot share folders where the user has a period in their name.

Suppose I log in as 'some.user' and do: SETACL INBOX mailtest@example.co.uk +lrwstipekxacd

/var/mail/virtual/users/some.user/Maildir/dovecot-acl is created, with appropriate contents and shared-mailboxes.db gains an entry for 'shared/shared-boxes/user/mailtest@example.co.uk/some.user@example.co.uk'. mailtest is simply unable to see a new folder.

As mailtest 'a LIST "" "Users.*" ' is empty. If I do ' a MYRIGHTS Users.some.user.INBOX ' I get 'NO [NONEXISTENT] Mailbox doesn't exist: Users.some.user.INBOX' and, oddly, a new maildir appears: '* LIST (\Noselect \HasChildren) "." "Users.some" ' -- it also creates an empty folder structure with a single file /var/mail/virtual/users/some/Maildir/dovecot-acl-list too!

Is there a workaround that does not involve rebuilding every user's Maildir with backslash as a separator?

Thanks,

Ian