`origin/HEAD` Not Present

origin/HEAD is a useful ref since it refers to the default branch, which varies between repos. origin/HEAD is normally present locally, so Git scripts, hooks, etc. that work locally sometimes rely on the presence of origin/HEAD and then break in GitHub Actions. I'm not aware of an input that allows one to ensure that this useful ref is present in a checkout. As a workaround, we run git remote set-head origin --auto manually, but it would be nice to have within the action since diagnosing the issue requires considerable familiarity with Git. In particular, I find the absence of origin/HEAD when passing fetch-depth: 0 counterintuitive.

Start by reviewing the checkout action's handling of fetch-depth and remote refs, then reproduce the behavior in GitHub Actions with fetch-depth: 0. Done means the action reliably provides origin/HEAD for scripts and hooks without requiring a manual git remote set-head origin --auto.