Revert accidental renaming of `packageKey`
Revert accidental renaming of `packageKey`

This was introduced accidentally via
b083151f2a01ad7245f21502fd20f21189ab7665

/cc @ezyang

themoritz/cabal,themoritz/cabal,mydaum/cabal,sopvop/cabal,sopvop/cabal,themoritz/cabal,mydaum/cabal,sopvop/cabal