pip install waring "SNIMissingWarning","InsecurePlatformWarning"

/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

ubuntu 版本14.04， python版本 2.7.6

解決方法：

sudo apt-get install python-dev libffi-dev libssl-dev

其餘系統版本

sudo pip install pyOpenSSL ndg-httpsclient pyasn1
Or
sudo pip install -U pyopenssl ndg-httpsclient pyasn1
Or
sudo pip install --upgrade pip
Or 
sudo pip install requests==2.5.3