升级过程如下：
brew updateerror: your local changes to the following files would be overwritten by merge: formula/php56.rbplease, commit your changes or stash them before you can merge.abortingerror: failed to update tap: homebrew/php

求解决方法
回复内容： 升级过程如下：
brew updateerror: your local changes to the following files would be overwritten by merge: formula/php56.rbplease, commit your changes or stash them before you can merge.abortingerror: failed to update tap: homebrew/php

求解决方法
找到解决办法了，如下
cd $(brew --prefix)/library/taps/homebrew/homebrew-phpgit checkout -- formula/php56.rb
另外很感谢@mcfog 提供的phpbrew，很值得推荐，我会尝试的
提示很明确啊，php56.rb本地被改过，需要还原才能更新
如果你不清楚怎么被改过的话，直接
bashcd /usr/local/library/formula/git reset --hard
还原全部formula文件就好
顺带继续推荐更好支持多php版本，编译更方便的phpbrew