sieve folder (dovecot.sieve) in directory path causes errors

Sieve 0.2.3d, a useful plugin for Thunderbird, puts sieve directories in 
the mail directory.  These directories are correctly identified as not a 
mail directory by Mulberry.  This generates an error in the error logs:

(Jun 16 09:54:52 imap([email protected]): Error: 
stat(/mail/domain.com/gessel//.dovecot.sieve/tmp) failed: Not a directory

It also seems to slow Mulberry down.

Mulberry's sieve editor doesn't seem to find the scripts.

TB ignores the folder.

Is there any way to get Mb to ignore the folder as well?  Unsubscribing 
doesn't seem to do it.

-David