these 2 derivations will be built:
  /nix/store/32vyv59cl8rkb5acpvgl4lckgvcq32hh-nixos-test-driver-pg_cron.drv
  /nix/store/zrqxw8glbxkgc1awd6hwds7z8py0xm57-vm-test-run-pg_cron.drv