Another active Homebrew process is already using mysql问题的解决方法

brew install mysqll命令执行到一半，屏幕锁屏了，结果重现打开进去后，进度不动了，Ctrl ＋ Z结束掉，然后：

chenzhixiangdeMacBook-Pro:my-yesod-project chenzhixiang$ brew install mysql
Error: Operation already in progress for mysql
Another active Homebrew process is already using mysql.
Please wait for it to finish or terminate it to continue.

见鬼。

解决方法：

$ rm $(brew --cache)/Formula/*

来源：http://blog.qiji.tech/archives/5739