these 4 derivations will be built:
  /nix/store/pznw0dfq62niyl2g24pi92zp1xd031aq-Cargo.toml.drv
  /nix/store/487yx773fk1wchr2i4s0nd1gws2dyzg9-source.drv
  /nix/store/4s8x7jfw3kyxplxy761jzf3qccj11wvi-harmonia-deps-3.2.0.drv
  /nix/store/739l1ybj9dwfhmyiqkcc2p8cflfqmm1h-harmonia-3.2.0.drv