Brew recently started refusing to install anything if your xcode is out of date, and forces you to wait for a "brew update" if it hasn't updated in 24 hours. It

Brew recently started refusing to install anything if your xcode is out of date, and forces you to wait for a "brew update" if it hasn't updated in 24 hours. It's actually hideously user-unfriendly, but it probably saves the devs a lot of stupid github issues.