[Dovecot] LAYOUT=fs still uses 'dot' prefixes for folders

running latest dovecot HEAD, per,

http://wiki.dovecot.org/MailLocation/Maildir

i've set LAYOUT=fs,

dovecot -n| grep -i layout
	mail_location: maildir:/data/mail:LAYOUT=fs

and expect,

maildirs to actually use physical directories, such as:
    * Maildir/folder/
    * Maildir/folder/subfolder/

but, autocreate@login creates folders using "dot" prefixes, e.g.,

cd /data/mail/Domains/my.domain.com/Accounts/test_account
ls -1d .*
	./
	../
	.Drafts/
	.Spam/
	.Templates/
	.Trash/

&, login via TBird, creating a folder "test", also creates

.test/

a bug, or a misconfiguration?