this derivation will be built:
  /nix/store/mw1i78cv7ia90nynlclvi2ykrq41362g-nix-shell.drv
this path will be fetched (8.2 MiB download, 68.6 MiB unpacked):
  /nix/store/b3g622hyfcczd99fpghjlrk37fflx2xr-rust-lib-src