emberjs/ember.js — pull request #3902 by stefanpenner (2013-12-10 15:23:53+00:00)
Title: Remove `RSVP.Promise#fail` in favor of `catch`.

After discussion with @wycats and @domenic, it was decided we should remove
`fail` before it enters an official release

- es3 users should use the ['catch'] syntax
- plans are to add a transpiler for people to es5 -> es3 (for finally and catch) etc.