Fix bug removing empty auto-inserted nodes 

* If the node is a template marker node, it cannot be removed.

* Exposed in https://gerrit.wikimedia.org/r/#/c/159624/

* Ex.

     http://localhost:8000/_rt/frwiki/Karl_von_Oven
     http://localhost:8000/_rt/ruwiki/%D0%9E%D0%B1%D0%B5%D1%80%D0%B8%D0%BD%D0%B3%2C_%D0%93%D0%B5%D0%BD%D1%80%D0%B8

Change-Id: I919fce8dbfa2b697dda941640e15718f6031c4e1