This repo demonstrate how to install pip's latest version
（注意安装顺序，否则安装之后pip就会指向pip3，必须首先安装pip3然后安装pip2）
这里会安装到/usr/lib/python2.7/dist-packages/pip和/usr/lib/python2.7/dist-packages/pip3这个位置了
安装pip3
sudo apt install python3-pip安装pip2
sudo apt install python-pip更新新的pip到/usr/local/lib/python2.7/dist-packages/pip和/usr/local/lib/python2.7/dist-packages/pip3这个位置了 更新pip3
sudo -H pip3 install -U更新pip3
sudo -H pip install -U sudo apt remove python3-pip python-pip pip config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple
pip3 config set global.index-url https://pypi.tuna.tsinghua.edu.cn/simple