horde/horde — pull request #104 by duritong (2014-09-21 14:00:25+00:00)
Title: it is possible that $this->_cache is empty

Fixing errors like:
WARN: HORDE [imp] PHP ERROR: Invalid argument supplied for foreach() [pid 123 on line 97 of "/var/www/vhosts/horde-dev.immerda.ch/www/imp/lib/Factory/MailboxList.php"]