[Zope] temporary_folder after upgrade from 2.6.4 to 2.7.0

Hi! Some time ago I upgraded Zope from 2.6.4 to 2.7.0. I now noticed, that the temporary folder is not mounted with ZODB Mount Points. The error message is: "/temp_folder temporary ** Something is in the way **". On a clean installation it just says OK. I guess the temporary folder is a leftover from the 2.6.4 installation. The problem is, I can't delete it and mount it correctly. Florian