Should Pantry.Hackage.indexRelFile be hard coded?

[mpilgrem]

Package.Hackage.indexRelFile has:

indexRelFile :: Path Rel File
indexRelFile = either impureThrow id $ parseRelFile "00-index.tar"

This is chosen because Pantry.Hackage.updateHackageIndexInternal uses:

HS.Cache
  { HS.cacheRoot = HS.fromAbsoluteFilePath $ toFilePath root
  , HS.cacheLayout = HS.cabalCacheLayout
  }

and cabalCacheLayout.cacheLayoutIndexTar :: CachePath is rp $ fragment "00-index.tar".

Perhaps indexRelFile should be a function of cabalCacheLayout.