this derivation will be built:
  /nix/store/8iww1dkg4p8aly21bn0igpqfaaks53w4-nix-shell.drv
this path will be fetched (1.6 MiB download, 4.3 MiB unpacked):
  /nix/store/2snvhw2fnx7bf5669x3fdyla9k9k9aa2-cargo-llvm-cov-0.9.0