Check that multiple `repl-overlays` can compose together
@args --repl-overlays
@args "${PWD}/extra_data/repl-overlays-compose-1.nix ${PWD}/extra_data/repl-overlays-compose-2.nix"
  nix-repl> var
  "abc"
  nix-repl> varUsingFinal
  "final value is: puppy"