Being to soon to evaluate the latest version of the Mac operating system, OS X El Capitan, I have found a small issue after upgrading to it try to update brew (The missing package manager for OS X).
Such issue won’t appear after a fresh El Capitan install, but after upgrading to it. It happens because of the upgrade process updates
/usr/local permissions to
root:wheel. After that you won’t be able to brew update anymore until you fix it.