Extra check when deleting single, isolated treenodes because the whole skeleton is deleted if that skeleton had erroneously two or more root nodes.
Extra check when deleting single, isolated treenodes
because the whole skeleton is deleted if that skeleton had
erroneously two or more root nodes.

htem/CATMAID,fzadow/CATMAID,htem/CATMAID,fzadow/CATMAID,fzadow/CATMAID,htem/CATMAID,htem/CATMAID,fzadow/CATMAID