rewrite config search, fixes #3372

git-svn-id: svn://develop.studip.de/studip/trunk@26010 c5b85792-5220-0410-ad23-ed5b6b8ad999
prevent sql error, fixes #3362

git-svn-id: svn://develop.studip.de/studip/trunk@26011 c5b85792-5220-0410-ad23-ed5b6b8ad999