these 2 derivations will be built:
  /nix/store/fnabal59zd8ajv3r6qxlfjm20mpxibjf-nixos-test-driver-postgis.drv
  /nix/store/xb0vn0d8bk2wjah4dbmfyxi4rsdr5k95-vm-test-run-postgis.drv