Dokku&#x2F;herokuish do indeed lock down to specific buildpacks [1]. You just happened to use a method that allowed you to use <i>any</i> version of that buildpack (multi-buildpack, which is provided by Heroku itself).<p>[1] <a href="https:&#x2F;&#x2F;github.com&#x2F;gliderlabs&#x2F;herokuish&#x2F;tree&#x2F;master&#x2F;buildpacks" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;gliderlabs&#x2F;herokuish&#x2F;tree&#x2F;master&#x2F;buildpac...</a>