Temporarily unset the kIsReferenced bit before cloning the object in order to...

Temporarily unset the kIsReferenced bit before cloning the object in order to avoid the (incorrect/unwanted) registration of the clone


git-svn-id: http://root.cern.ch/svn/root/trunk@23057 27541ba8-7e3a-0410-8455-c3a389f83636