these 2 derivations will be built:
  /nix/store/gqclm50an0dkgvxvd5jxk87km76hanns-nixos-test-driver-pg_cron.drv
  /nix/store/r4b6kcgj2c7w88ic4vylllvhp52sirm6-vm-test-run-pg_cron.drv