these 2 derivations will be built:
  /nix/store/wazf4xqwpifzjjfm3zkckrwhpz7wzz81-nixos-test-driver-postgis.drv
  /nix/store/rzdyayzj1mqh12ap4xzv2pizg99m0y4q-vm-test-run-postgis.drv