Installing Ruby 2.0 on OS X with RVM

This was moderately tedious to get running so I thought I'd post some goodies up here on how to do it.

I was seeing a failure like this

No binary rubies available for: osx/10.8/x86_64/ruby-2.0.0.
Continuing with compilation. Please read 'rvm mount' to get more information on binary rubies.
Installing Ruby from source to: /Users/drpep/.rvm/rubies/ruby-2.0.0, this may take a while depending on your cpu(s)...
ruby-2.0.0 - #downloading ruby-2.0.0, this may take a while depending on your connection...
Error running '/Users/drpep/.rvm/scripts/fetch http://ftp.ruby-lang.org/pub/ruby/2.0/ruby-2.0.0.tar.bz2', please read /Users/drpep/.rvm/log/ruby-2.0.0/fetch.log
There has been an error fetching the ruby interpreter. Halting the installation.

Turns out, all I needed to do was achem get head.

rvm get head

Then

rvm autolibs enable

to allow rvm to download dependencies for without barfing; and finally

rvm install ruby-2.0.0

Happy days, the world was good.

As you were. :)