Long-running branches are painful, but upgrading to Rails 3 requires one if you can't stop development, right? Wrong! At New Relic, we worked on upgrading to Rails 3 on master while letting development continue in Rails 2. We patched Bundler, built a backwards-compatible boot sequence, and punched ActiveScaffold in the face. Other developers, meanwhile, released 1400 commits worth of work without noticing any changes. We’ll talk about what we did, why we did it, and why we think this approach can help developers get over the hurdle into the Rails 3 promised land.