Fix tree name identification when >1 levels of dirs
Fix tree name identification when >1 levels of dirs

Fixes issue reported on the forum (http://root.cern.ch/phpBB3/viewtopic.php?f=13&t=17605)

tc3t/qoot,kirbyherm/root-r-tools,tc3t/qoot,tc3t/qoot,kirbyherm/root-r-tools,tc3t/qoot,kirbyherm/root-r-tools,kirbyherm/root-r-tools,tc3t/qoot,kirbyherm/root-r-tools,tc3t/qoot,kirbyherm/root-r-tools,kirbyherm/root-r-tools,tc3t/qoot,tc3t/qoot,tc3t/qoot,tc3t/qoot