these 2 derivations will be built:
  /nix/store/6hfdnq4x4lrsiszdj7xnwamjjhvicips-lean-ctx-3.10.2-vendor.drv
  /nix/store/5xqrkm4qd43n70vxrck7sqj8qs1qpnsm-lean-ctx-3.10.2.drv