these 2 derivations will be built:
  /nix/store/g6lfx52nxlxww5k9wqsvyw2198jjcj01-nixos-test-driver-pgtap.drv
  /nix/store/6gacnx157yxzqzyq95wgsk8kl3p3m22d-vm-test-run-pgtap.drv