should CLEAN be deprecated?

`do_build()` ends with 
```
...
    invoke_command "$clean" "Cleaning build area" "$build_log" background
    cd - >/dev/null || exit 15
    mv -f "$build_log" "$base_dir/log/make.log" 2>/dev/null
    rm -rf "${build_dir:?}"
```

Do we really need to clean the `$build_dir` before deleting it?