Rails 4.2+ apps will have RAILS_SERVE_STATIC_FILES set by default

Change effective on 02 March 2015

Rails applications 4.2 and above will have the environment variable RAILS_SERVE_STATIC_FILES set to enabled by default. This will allow a new Rails 4.2+ app to serve static assets by default as a result of this pull request to Rails. For more details on implementation, see the Ruby Buildpack’s PR.