-----> Ruby/Rack app detected -----> Using Ruby version: ruby-1.9.3 -----> Installing dependencies using Bundler version 1.3.0.pre.2 Running: bundle install --with
UPDATE: This answer doesn't work. The only option is to raise a support ticket.
There's a new feature that fixes this problem:
$ heroku config:set COMPILE_TIMEOUT=n
where n is a number in seconds. I used n=3000 (default is 900).
(note: you may need user-env-compile enabled to use this feature)
Update: Please read the comments on this answer for updated information!