Re: detached HEAD before root commit - possible?

[Junio C Hamano <gitster@pobox.com>]

Martin von Zweigbergk <martinvonz@gmail.com> writes:

> On Sun, Jun 23, 2013 at 4:54 PM, Jonathan Nieder <jrnieder@gmail.com> wrote:
>>
>> In other words, HEAD always either points to an unborn or existing
>> branch or an existing commit.  It's not clear to me what it would
>> mean to detach from an unborn branch.
>
> I think it should mean that the next commit would be a root commit (of
> course) and that HEAD would be detached and point to that commit.

Yup.  As Jonathan outlined how the current system works:

 - $GIT_DIR/HEAD could be a symref to a branch, which may or may not
   exist (the latter being "unborn"); or

 - $GIT_DIR/HEAD could be directly pointing at an existing commit,
   which is the definition of "detached", as you "detach HEAD at
   that commit".

even though such a "I do not have any commit and I will not be on
any branch" state were to be supported, the consequence of that
would be that a natural implementation of such a state is to
represent it by not having $GIT_DIR/HEAD at all.  That will break
quite a lot of things, as such a directory $GIT_DIR will not be
treated as a git directory in the first place.  Of course, you could
fix them up to support it, but I doubt if it is worth the trouble.