According to https://github.com/Homebrew/brew#update-bug
If Homebrew was updated on Aug 10-11th 2016 and brew update always says Already up-to-date. you need to run
cd $(brew --repo); git fetch; git reset --hard origin/master; brew update
According to https://github.com/Homebrew/brew#update-bug
If Homebrew was updated on Aug 10-11th 2016 and brew update always says Already up-to-date. you need to run
cd $(brew --repo); git fetch; git reset --hard origin/master; brew update