Re: HEAD's reflog entry for a renamed branch

> It's unfortunate that there's no message. This is because the rename
> calls delete_ref() under the hood, but that function doesn't take a
> reflog message argument at all. It usually doesn't matter because
> deleting the ref will also delete the reflog.
>
> But as your example shows, deletions _can_ get logged in the HEAD
> reflog; the low-level ref code detects when HEAD points to the updated
> ref and logs an entry there, too.
> ...
> I'd say there are two potential improvements:
>
>   - delete_ref() should take a reflog message argument, in case it
>     updates the HEAD reflog (as a bonus, this will future-proof us for a
>     day when we might keep reflogs for deleted refs).

>   - "git branch -m" does seem to realize when we are renaming HEAD,
>     because it updates HEAD to point to the new branch name. But it
>     should probably insert another reflog entry mentioning the rename
>     (we do for "git checkout foo", even when "foo" has the same sha1 as
>     the current HEAD).