> brew update; brew upgrade
Warning: Could not create link for jingweno/ccat/ccat, as it
conflicts with Homebrew/homebrew/ccat. You will need to use the
fully-qualified name when referring this formula, e.g.
brew install jingweno/ccat/ccat
Updated Homebrew from 84dd2e2f to d956958c.
==> New Formulae
ccat
...
seems formula have been added upstream: https://github.com/Homebrew/homebrew/commit/f8e10bbd42a9eeae801499fbfdb27e49b9b88c5e
one solution is to remove this tap:
brew untap jingweno/ccat