depois de postar nos problemas do github homebrew:https://github.com/mxcl/homebrew/issues/11762
aqui está como eu corrigi o problema:
cd /usr/local
brew uninstall cmake
git checkout 948c2769 Library/Formula/cmake.rb
brew install mysql
cd /usr/local
brew uninstall cmake
git checkout 948c2769 Library/Formula/cmake.rb
brew install mysql
