these 2 derivations will be built:
  /nix/store/n7vmk1gbmdb9wi222pa0mmfvcdx91n3k-nixos-test-driver-pg_cron.drv
  /nix/store/227rjx86m8nw2n8c06hw4wb2nipv9xa9-vm-test-run-pg_cron.drv