$ brew update
error: The following untracked working tree files would be overwritten by merge:
Library/Formula/libmusicbrainz.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 Solution:
rm /usr/local/Library/Formula/libmusicbrainz.rb
brew update