最近brew出了个问题，更新的时候出现这个错误：


xiaoshan:public xiaoshan$ brew update
error: The following untracked working tree files would be overwritten by merge:
	Library/Formula/osm2pgsql.rb
Please move or remove them before you can merge.
Aborting
Error: Failure while executing: git pull -q origin refs/heads/master:refs/remotes/origin/master

最后找到如下解决方案：


cd `brew --repository`
git reset --hard HEAD
brew update

如果不行，试试下面这个:


cd `brew --repository`
git reset --hard origin/master
brew update


解决方案来自: http://stackoverflow.com/questions/9966191/homebrew-update-irritating-error-message