requiring sudo during installation

[christopherowen]

Could we please check if the permissions are set correctly on /Library/Caches/Homebrew before requesting a password be entered?

If the permissions are already set correctly on the folder we shouldn't attempt to run chmod.

I'm specifically referring to this step of the brew installation process:

==> /usr/bin/sudo /bin/chmod g+rwx /Library/Caches/Homebrew
Password:

[jacknagel]

Please file this against https://github.com/Homebrew/install/blob/master/install, where the installer is maintained. Thanks!