…23606)

Reference:
go-gitea#22578 (comment)

Credits to @tdesveaux , thank you very much for catching the problem. If
you'd like to open a PR, feel free to replace this one.

Git reports fatal errors for ambiguous arguments:

```
fatal: ambiguous argument 'refs/a...refs/b': unknown revision or path not in the working tree.
        Use '--' to separate paths from revisions, like this:
        'git <command> [<revision>...] -- [<file>...]'
```

So the `--` separator is necessary in some cases.