these 3 derivations will be built:
  /nix/store/9a0wvr5nshxmmlga51yxxmjyfv7mgh6b-lean-ctx-3.9.14-vendor-staging.drv
  /nix/store/akfxxyk4nzy0rdnsra46kxg79l4pr44i-lean-ctx-3.9.14-vendor.drv
  /nix/store/jimkc9qnx4qc7hv5is1zk1hnxxv35f2s-lean-ctx-3.9.14.drv