I can't delete my Old Tag Set Properties

(Bug, Closed -> Fixed, Priority: Medium, Test Status: No automated tests yet , Reported By Justin du Coeur, )
Tag Sets
Summary: In my Recipes Space, I have an "Old Equipment" Property, which is one of the Old Tag Sets. For the life of me, I can't get the damned thing off of my Things. Investigate this, and figure out why not.
Turned out to have nothing to do with Old Tag Set -- the problem was actually that you couldn't delete Properties if Instance Properties was set. There was even a TODO comment in the code about that. Now fixed: the code has been enhanced to let you delete a Property even in the presence of Instance Properties.