these 2 derivations will be built:
  /nix/store/nk89v68jv02i9m7brz5vb0ln0n4mrx4x-nixos-test-driver-postgis.drv
  /nix/store/60zb55k10q1l37prfj9ybh092v1s01wi-vm-test-run-postgis.drv