heroku/heroku-buildpack-ruby — pull request #114 by schneems (2013-06-26 17:40:32+00:00)
Title: Verify Rails 3 to 4 without ./bin works

Looks like it is good to go. Using new major release of Hatchet that fixed all sorts of compatibility issues with running interactive consoles. Split all of that code into a separate lib: https://github.com/schneems/repl_runner

ATP, looks like code on master is good to go.