Can this shuffling algorithm be pulled out into a helper module?  It would be nice to have it self-contained.  Plus, once you do that, you can move the `if RUBY_VERSION` conditional out into the module definition so that it is only evaluated once (rather than every time).  For example, it could be something like this:

``` ruby
module RSpec
  module Random
    if RUBY_VERSION > '1.9.3'
      def self.shuffle(list, random_number_generator)
        list.shuffle(:random => random_number_generator)
      end
    else
      def self.shuffle(list, random_number_generator)
        # your implementation
      end
    end
  end
end
```