I've gotten this error after running "brew update"
Homebrew seems to be having lots of errors with some Ruby files. Any hints on how to proceed from here would be appreciated, thanks
homebrew is just a git repo. You can cd $(brew --prefix) and ensure that there's no local changes that are messing up with your update.
When you do brew update you should be getting a larger output than just the failure. If you post that we may be able to help you better.
To do a quick fix if you don't care about any changes made in your homebrew installation, simply cd into the homebrew repo using the command above and run git reset --hard origin/master. You should then be able to do the update.