我想这样做pip install，但是它说：
/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:122:
InsecurePlatformWarning: A true SSLContext object is not available.
这会导致 urllib3 无法正确配置 SSL，并可能导致某些 SSL 连接失败。您可以升级到较新版本的 Python 来解决此问题。有关更多信息，请参阅https://urllib3.readthedocs.io/en/latest/security.html#insecureplatformwarning。
所以我注意到发布了一个新版本的 Python 加密库。想通过 synaptic 更新我的系统。安装程序卡在安装 bind9（停止 bind9 服务）上。停止该过程，重新启动我的系统。之后 apt-get 没有说需要更新 python，但 pip install 仍然不起作用。
我认为这与 pip 更新无关：
sudo -H pip2 install --upgrade pip
/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:318: SNIMissingWarning: An HTTPS request has been made, but the SNI (Subject Name Indication) extension to TLS is not available on this platform. This may cause the server to present an incorrect TLS certificate, which can cause validation failures. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/security.html#snimissingwarning.
SNIMissingWarning
/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:122: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/security.html#insecureplatformwarning.
InsecurePlatformWarning
Requirement already up-to-date: pip in /usr/local/lib/python2.7/dist-packages
/usr/local/lib/python2.7/dist-packages/pip/_vendor/requests/packages/urllib3/util/ssl_.py:122: InsecurePlatformWarning: A true SSLContext object is not available. This prevents urllib3 from configuring SSL appropriately and may cause certain SSL connections to fail. You can upgrade to a newer version of Python to solve this. For more information, see https://urllib3.readthedocs.io/en/latest/security.html#insecureplatformwarning.
InsecurePlatformWarning