these 2 derivations will be built:
  /nix/store/a4kbqzgh62xws4v4kgsfjc5ri9bqd9m1-nixos-test-driver-postgis.drv
  /nix/store/bbhjjfjs6n62adjxrqrhi2gvhi9sb15d-vm-test-run-postgis.drv