If you ever come across this error while trying to update homebrew on your Mac:
error: The following untracked working tree files would be overwritten by merge:
Please move or remove them before you can merge.
Error: Failure while executing: git pull -q origin refs/heads/master:refs/remotes/origin/master
just, do this:
$ rm /usr/local/Library/Formula/cocot.rb
I have no idea what cocot.rb is for, or where it came from. All I know is that it is preventing homebrew from updating, so I just deleted it, and everything was fine again.
In case you are afraid to delete, do this instead:
$ mv /usr/local/Library/Formula/cocot.rb /usr/local/Library/Formula/cocot.rb.bak
Once done, update homebrew successfully:
$ brew update
... Updated Homebrew from 8d9fd732 to 560df359.