Kali Linux: Ошибка при установке cython

При

python3 -m pip install cython

Выдает

WARNING: Running pip as the 'root' user can result in broken permissions and conflicting behaviour with the system package manager. It is recommended to use a virtual environment instead: https://pip.pypa.io/warnings/venv

При

git clone https://github.com/oremanj/python-netfilterqueue

Выдает

fatal: destination path 'python-netfilterqueue' already exists and is not an empty directory.