Homebrew update出錯

Homebrew升級報錯：

$brew update
....
error: The following untracked working tree files would be overwritten by merge:
	.github/CONTRIBUTING.md
	.github/ISSUE_TEMPLATE.md
	.github/PULL_REQUEST_TEMPLATE.md
	etc/bash_completion.d/brew
	share/doc/homebrew/Analytics.md
	share/doc/homebrew/Checksum_Deprecation.md
	share/doc/homebrew/Kickstarter-Supporters.md
	share/doc/homebrew/Maintainers-Avoiding-Burnout.md
	share/doc/homebrew/Node-for-Formula-Authors.md
	share/doc/homebrew/Prose-Style-Guidelines.md
export CLASSPATH
	share/doc/homebrew/images/analytics.png
	share/doc/homebrew/images/brew-test-bot-failed-jenkins.png
	share/doc/homebrew/images/brew-test-bot-failed-pr.png
	share/doc/homebrew/images/brew-test-bot-failed-test.png
	share/doc/homebrew/images/brew-test-bot-passed-jenkins.png
	share/doc/homebrew/images/brew-test-bot-passed-pr.png
	share/doc/homebrew/images/brew-test-bot-triggered-pr.png
	share/zsh/site-functions/_brew
Please move or remove them before you can merge.
Aborting
Error: Failure while executing: git pull --ff --no-rebase --quiet origin refs/heads/master:refs/remotes/origin/master

解決辦法：

git remote add origin https://github.com/Homebrew/homebrew.git
git fetch origin
git reset --hard origin/master
brew update