centos 安装 pip

 
work around:

$ wget https://bootstrap.pypa.io/get-pip.py
$ sudo python get-pip.py
$ pip -V
pip 9.0.1 from /usr/lib/python2.7/site-packages (python 2.7)

https://stackoverflow.com/questions/35560331/cannot-install-pip-centos-6-7