Fixes a weird test hanging bug caused by our nested use of `make`
Fixes a weird test hanging bug caused by our nested use of `make`

Some special GNU Make environment variables set by `make test` were
affecting our planner, which relies on Make.

zifeishan/deepdive,zifeishan/deepdive,HazyResearch/deepdive,zifeishan/deepdive,HazyResearch/deepdive,sky-xu/deepdive,HazyResearch/deepdive,shahin/deepdive,zifeishan/deepdive,zifeishan/deepdive,shahin/deepdive,HazyResearch/deepdive,sky-xu/deepdive