these 2 derivations will be built:
  /nix/store/3zfds7n79bsxhasa3lqiw7kjf9jlc4x3-nixos-test-driver-postgis.drv
  /nix/store/7wfqsbrdg4jvqwwikqwzbsppy9bpx9km-vm-test-run-postgis.drv