Change effective on 26 February 2016
Heroku’s support for PHP application received several updates today; below is a list of the most important changes.
Applications that utilize a custom
composer.phar will no longer get
composer aliased to that custom file at runtime. A custom
composer.phar will only be used during builds.
PHP applications on Heroku may now use their own platform repositories to use custom builds of web servers, runtimes, or extensions without having to run a forked version of the buildpack. This is an experimental feature, and no support is offered for issues related to this functionality.