pip install SSLError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443):

python 在安装安装包的时候会报如下错误：

SSLError: HTTPSConnectionPool(host='files.pythonhosted.org', port=443): Max retries exceeded with url: /packages/77/41/706fc9525f195a41b89718cdb7b36bd2e1cbf448842699e80152befe00a5/Active-SQLAlchemy-0.4.0.tar.gz (Caused by SSLError(SSLError(1, u'[SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:765)'),))

解决办法：把报错的域名添加到信任列表中去，可以添加多个受信任的域名

pip --trusted-host pypi.python.org --trusted-host pypi.org install --trusted-host files.pythonhosted.org  Active-SQLAlchemy==0.4.0