Revert "Fix data races, simplify"

This reverts commit f61e211a1e8fb92ac298997f600bea2bcbd20e33.

This actually breaks the semantics of how the state is changed mid-step.
I realize it is a race but it is a race that Packer currently depends
on. I think the proper solution is to fix the state bag.

Sorry, @titanous, I'll address these soon.