安裝遇到問題：ERROR: Cannot uninstall 'Werkzeug'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.
將下載命令改爲：
pip install --ignore-installed six
或更普遍
pip install --ignore-installed ${PACKAGE_NAME}
如圖：
安裝成功。
感謝https://github.com/blockstack/blockstack-core/issues/504 提供的解答。