`next-status` claims nothing to save when all is staged and no HEAD

[mih]

Clearly misleading and wrong

❯ git status
On branch main

No commits yet

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)
        new file:   datasalad/__init__.py
        new file:   pyproject.toml

❯ datalad next-status
nothing to save, working tree clean