Mac上面不能安装Homebrew

这个stackoverflow的答案解决了我的问题：

http://stackoverflow.com/questions/18039029/mac-can-t-install-homebrew

问题如下：

it appears Homebrew is already installed. If your intent is to reinstall you
should do the following before running this installer again:
rm -rf /usr/local/Cellar /usr/local/.git && brew cleanup

解决方案：

rm -rf /usr/local/Cellar /usr/local/.git
ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"