重置 conda 环境

有时候不小心把库装到错误的环境里，一个个卸载又很麻烦，使用下面的方法：

第一步：conda list --revisions
第二步：conda install --revision REV_NUM

EDIT: be careful though if you execute conda install --revision 0 as this will remove your root environment and the conda command. Maybe conda install --revision 1 would produce the desired behavior (restore root environment to its state after first installation).