these 2 derivations will be built:
  /nix/store/md9hjzglfm8l0psx144xbqna9wk4zd6g-nixos-test-driver-pgtap.drv
  /nix/store/xywnsr1ykf3n0vbk2g4swc98wp1dffwb-vm-test-run-pgtap.drv