Add even simpler test for double-splice problem
Add even simpler test for double-splice problem

Specifically, the problem here is that variants *also* potentially need to
create variants of the programs they *contain*. This suggests that the right
IR is not a flat table of programs but a recursive structure, so we can
specialize a whole subtree.

cucapra/braid,cucapra/braid,guoyiteng/braid,guoyiteng/braid,guoyiteng/braid,guoyiteng/braid,guoyiteng/braid,guoyiteng/braid,cucapra/braid,cucapra/braid,cucapra/braid,cucapra/braid