these 2 derivations will be built:
  /nix/store/7nzmp8nlnimg1mpqzs3ygm3c03g4qmv2-nixos-test-driver-pgtap.drv
  /nix/store/ykwjdb830010h6p27866rb2ylrwna1x8-vm-test-run-pgtap.drv