Change effective on 23 March 2016
Previously Heroku would cache the contents of
.bundler/config file that was generated after installing dependencies during a deploy via:
$ bundle install
This behavior was fine for Bundler 1.9.7 but after a change introduced in 1.10 this could result in a configuration option from being persisted permanently with no way to remove it. Heroku has upgraded Bundler to version 1.11.2 which exhibits this changed behavior. By no longer caching
.bundle/config files between builds, the deploy behavior will be closer to how it was when Heroku was using bundler 1.9.7.
If you need to configure your bundle install behavior please see Bundler configuration documentation.