升级docker无法解决我的问题。相反，我必须将反向端口安装为Ubuntu软件包（并从pip卸载）：

Upgrading docker didn't solve the problem for me. Instead, I had to install the backports as Ubuntu package (and uninstall from pip):

sudo pip uninstall backports.ssl-match-hostname
sudo apt-get install python-backports.ssl-match-hostname