these 2 derivations will be built:
  /nix/store/qc2v09mmrdxpnylp08kdhvyh0c0yzydq-nixos-test-driver-pg_cron.drv
  /nix/store/agah6zx93lmjy3ygl73abbrzpyxgxasi-vm-test-run-pg_cron.drv