Govendor is now the default vendoring tool for Go

Change effective on 02 September 2016

Govendor is now the primarily supported vendoring tool for Go code on Heroku. We will continue to support Godep for the immediate future, but we feel govendor provides a superior experience.

All sample applications and related docs have been updated to reflect this change.

Heroku also supports GB. Glide support is a work in progress.