Python升级pip到18.1遇到问题

前情提要:

　　安装新环境，pip install package时提示要升级pip到18.1，提示

You are using pip version 10.0.1, however version 18.1 is available.
You should consider upgrading via the 'python -m pip install --upgrade pip' command.

　　按照提示升级后，报错:　

AttributeError: 'NoneType' object has no attribute 'bytes'

 

解决:　　

　　用easy_install

easy_install -U pip

　　安装上了，验证

pip -V