fix(git): handle properly detached HEAD ref

[neilime]

Properly manage detached HEAD when getting ref.

• Check if we are in a detached HEAD context
• If so handle detached tag and branch context

[crazy-max]

LGTM thanks

Just to clarify, did you encounter an issue with the current API? I guess with metadata-action?

[neilime]

@crazy-max by example:

If I'm checking out a pull request branch (Needed on issue_comment event by example):

  - uses: actions/checkout@v3
    with:
      ref: refs/pull/${{ github.event.issue.number }}/head

  - uses: docker/metadata-action@v5.0.0

I got the following error

Error: fatal: No names found, cannot describe anything.