[bp/r52877][FIX] treetable: Reset parent node if not setting it.
Should fix group inheritance listing errors on tiki-objectpermissions.php
Also remove redundant $id statement.

git-svn-id: file:///var/local/code.tiki.org/tikisvn/branches/12.x@52878 b456876b-0849-0410-b77d-98878d47e9d5