these 2 derivations will be built:
  /nix/store/1zzkx6fbsfwziwsjv5yyrl3vmd2a7v3r-nixos-test-driver-postgis.drv
  /nix/store/r56wxd3r1r2p20d8w1q9qkr425z03wxm-vm-test-run-postgis.drv