revert &tree-head XX static
revert &tree-head XX static

performance concerns are probably overblown, though if urbit.org gets 2x slower this commit is probably why

ohAitch/arvo,ohAitch/arvo,joemfb/arvo,ngzax/urbit,ngzax/urbit,urbit/urbit,Fang-/arvo,ngzax/urbit,jfranklin9000/urbit,cgyarvin/arvo,urbit/urbit,ngzax/urbit,solri/arvo,ngzax/urbit,urbit/urbit,jfranklin9000/urbit,urbit/urbit,ngzax/urbit,jfranklin9000/urbit,joemfb/arvo,cgyarvin/arvo,urbit/urbit,jfranklin9000/urbit,jfranklin9000/urbit,jfranklin9000/urbit,urbit/urbit,jfranklin9000/urbit,ngzax/urbit,belisarius222/arvo,urbit/urbit,belisarius222/arvo