Heroku deployment with circleci 2.0


Looking at the Fan-in-out example - https://github.com/CircleCI-Public/circleci-demo-workflows/tree/fan-in-fan-out/.circleci

I’m trying to do a similar heroku deploy with circleci v2.0. I’m looking at the command on line 93 in the deploy job of the config.yml I can’t understand how the assets, restored from the previous jobs, are added to git? In my build I get failures telling me the build artifacts I am trying to push to the remote heroku git repo haven’t been added and there’s nothing to push.

According to this document - https://devcenter.heroku.com/articles/git you need to run

git init
git add
git commit

before pushing the build to heroku’s repo from where it is deployed. I have added those commands before pushing but I then get errors such as

*** Please tell me who you are.

even though Ive added the user credentials by runing the setup-heroku.sh script.

am I missing something?