Using Rails 3 edge to circumvent current_period bug?

I get an error using Rails 3 beta3 on Ruby 1.9.2-preview1

undefined method `current_period' for nil:NilClass (NoMethodError)

This commit should fix it

http://github.com/rails/rails/commit/a0cc94b32e5b4e4dce50787eed1208406f99ea82

But I forgot how to ensure I am running on edge with Rails 3.
Is it a special bundler command I need to use?

Thanks!

Hmm, I guess I could just clone github rails and then use the :path
option in my Gemfile to point to that version, but is there another
way?

The other option would be to use the :git=>"git://...." syntax with bundler.

Thanks. I've just been away from Rails dev for a bit too long...

# Bundle edge Rails instead:
gem 'rails', :git => 'git://github.com/rails/rails.git'