在用pip7.1.2版本安装第三方模块时出现了如下警告：
/usr/lib/python2.7/site-packages/pip-7.1.2-py2.7.egg/pip/_vendor/requests/packages/urllib3/util/ssl_.py:90:
InsecurePlatformWarning: A true SSLContext object is not available.
This prevents urllib3 from configuring SSL appropriately and may
cause certain SSL connections to fail. For more information, see
https://urllib3.readthedocs.org/en/latest/security.html#insecureplatformwarning.
解决方法
yum -y install python-devel libffi-devel openssl-devel
pip install pyopenssl ndg-httpsclient pyasn1