当改变Python版本后，安装某个曾安装的模块，报错：

Command "python setup.py egg_info" failed with error code 1 ...

参考：https://stackoverflow.com/questions/35991403/pip-install-returns-python-setup-py-egg-info-failed-with-error-code-1

If it’s already installed, try

pip install --upgrade setuptools

If it’s already up to date, check that the module ez_setup is not missing. If it is, then

pip install ez_setup

然后重新安装，问题解决。