OK, thanks for that info!
For reference, I sorted out how to do this manually, so in case it’s helpful for others stumbling on this:
- Checkout a new branch
git checkout -b feedback
- Reset to the first commit
git reset --hard $(git rev-list --max-parents=0 HEAD)
- Push to the student repo
git push -u origin feedback
- Open a pull request from the default branch to
feedback