[imp] Undefined index: 1:* in MailboxCache.php

[Volker Then]

After a HEAD update I'm getting this when trying to empty Trash:

Notice: Undefined index: 1:* in 
/var/www/html/horde-cvs/imp/lib/IMAP/MailboxCache.php on line 285

Warning: Cannot modify header information - headers already sent by 
(output started at 
/var/www/html/horde-cvs/imp/lib/IMAP/MailboxCache.php:285) in 
/var/www/html/horde-cvs/imp/mailbox.php on line 247