Wow... Extensions all busted in latest TEST.
I think a heads up of "Extensions that touch any sheets will be completely busted" would be a good warning for this TEST version.
It kills me every time I read "to make it easier" my skin crawls because I know its going to break everything in extension land.
I've not investigated a lot - but changing names of anything in an established sheet has to be known to be a death blow to any extensions that work in it. Something you should warn in big red letters when you announce a TEST version as I figured this was a no impact when I first read it.
[Post Edit: Some critical stuff (for me) was rewritten so I'm less effected by the release now.]