Homebrew errors in Mac OS Mavericks when trying to install scala

The installation went fine, it's just not providing a symbolic link to /usr/local/bin, because it's "afraid" of messing around with macports.

As it says in the doctor message, first change the permissions in /usr/local/etc:

chown <username> /usr/local/etc

probably with sudo prepended (sudo chown <username> /usr/local/etc).

Now brew can update the necessary files and link scala:

brew link scala

and you might be fine.