This supports simplified loading buildpacks from a private git repository / repositories.
It hooks in only to the
compile stage of each buildpack.
custom-ssh-key-buildpack or similar.
.heroku-private-buildpacks file in the project root:
email@example.com:user1/private-repo1 firstname.lastname@example.org:user2/private-repo2 # ...
Copy the snippet above into CLI.