Today I was playing around with R 3.1 and suddenly I wanted to submit a patch. Following the guide I tried to 'bundle' to be able to run the tests. OOPS!

Well, if your gem building joy is interrupted by a 404 trying to fetch the ruby source mentioned in your RVM, (for me Looking for http://ftp.ruby-lang.org/pub/ruby/1.9/ruby-1.9.2-p274.tar.gz), you can use a dirty workaround and install the specific gem with a flag:

gem install some_gem -- --with-ruby-include=/your_home/.rvm/src/ruby-1.9.2-head

/peace