ruby on rails - Heroku and Emberjs Rails4 deployment -

the case pretty simple describe. gem file

gem 'ember-rails' gem 'ember-source', '1.0.0.rc6.2' gem 'handlebars-source', '~> 1.0.12' 

this application.js file

//= require jquery //= require jquery_ujs //= require foundation //= require handlebars //= require ember //= require ember-data //= require_self //= require q 

this have in development.rb , production.rb

config.ember.variant = :development config.ember.variant = :production   

i tested in production environment locally, worked fine. when push heroku, have following error, can't figure out problem

 -----> preparing app rails asset pipeline    running: rake assets:precompile    rake aborted!    couldn't find file 'handlebars'    (in /tmp/build_2ddhwlktd9evz/app/assets/javascripts/application.js:17) 

i forgot mention using rails4

try following in gemfile:

gem 'ember-rails' gem 'ember-source', '1.0.0.rc6' gem 'handlebars-source', '1.0.0.rc4' 

i using rails4 , working me.