these 2 derivations will be built:
  /nix/store/vfi1b9nsqvc3sbbkny7wrvzmv40sm8nv-nixos-test-driver-pg_repack.drv
  /nix/store/k5d3c8japwf5zn6bh1s05m7d5vb6mr6n-vm-test-run-pg_repack.drv