these 2 derivations will be built:
  /nix/store/qsfbdx3m6f4630b17y9vk5g70rq3pxp7-nixos-test-driver-pg_cron.drv
  /nix/store/ryslwgh6isnjk1ybkv0yan7245bb088g-vm-test-run-pg_cron.drv