message: Update rustup.sh for the moved dir of the sysroot source
diff: @@ -18,9 +18,9 @@ case $1 in
  ./clean_all.sh
  - (cd build_sysroot && cargo update)
  -
  ./y.rs prepare
  +
  + (cd download/sysroot && cargo update && cargo fetch && cp Cargo.lock ../../build_sysroot/)
  ;;
  "commit")
  git add rust-toolchain build_sysroot/Cargo.lock
  