how to manually deploy Heroku review app from a branch in a forked repository?

Question

How can we manually deploy a Heroku review app that is based on a branch in a Git repository that is forked from the Git repository to which the root Heroku app is directly-connected? The Heroku UI only appears to allow us to manually deploy from branches in the root app's Git repository, but not when the branch is a fork.

Answer 1

Forks do not exist in git context. It's something that was made popular by GitHub. So in short you can't.
Heroku cannot see the branches of forks.

You will have to visit the forked repo and build a connection from there. Though if you are not the owner/collaborator you can't do it through Heroku's dashboard.

If you start using app.json in your project (and the forks have that app.json file as well) you can then deploy your project through Heroku Buttons.

https://devcenter.heroku.com/articles/heroku-button