these 2 derivations will be built:
  /nix/store/difv2wmm7xvdd7j9mkh10ichl4h9liw7-Handy_0.9.6_amd64.deb.drv
  /nix/store/80v01dhfd88nb23gg0w54fmc3ryj0fz0-handy-0.9.6.drv