these 2 derivations will be built:
  /nix/store/cdsx919q5jfm1d0fp2kgaacp8ca8r4x7-cargo-vendor-dir.drv
  /nix/store/l4arbrxhbffy60b1nwiw3n053wzp1sdb-fast-nix-gc-proptest-0.1.0.drv