Everything goes well in local machine with assets pipeline in Rails 4 and Ruby 2.0. But when deploying to heroku, it is shown that: -----> Preparing app for Rails asset pipeline Running: rake assets:precompile I, [2013-03-12T03:28:29.908234 #912] INFO -- : Writing /tmp/build_1n6yi8lwna3sj/public/assets/rails-2ee5a98f26fbf8c6c461127da73c47eb.png I, [2013-03-12T03:28:29.914096 #912] INFO -- : Writin