these 2 derivations will be built:
  /nix/store/ys2ybgf12m0xw6cacgpy8bjay676w3gh-nixos-test-driver-pg_cron.drv
  /nix/store/lmxki8wp4vvvi06cw3kiilrr2jmf5z7v-vm-test-run-pg_cron.drv