Re: [PATCH v1 4/6] Expanded branch header for Porcelain Status V2

[Jeff Hostetler <git@jeffhostetler.com>]

On 07/21/2016 11:46 AM, Johannes Schindelin wrote:
> On Wed, 20 Jul 2016, Jeff King wrote:
>
>> On Wed, Jul 20, 2016 at 02:20:24PM -0400, Jeff Hostetler wrote:
>>
>>>> IIRC, it happens when HEAD points to a broken ref. So something like:
>>>>
>>>>     git init
>>>>     echo broken >.git/refs/heads/master
>>>>
>>>> would cause resolving HEAD to return NULL.
>>>
>>> That worked and I see "(unknown)".
>>>
>>> This is a bit of a nit, but is there a value we'd like
>>> to see there, such as "(unknown)" or "(broken)" or "(missing)"
>>> in that case?  (And make it clear that this is a different
>>> case from "(detached)".)
>>>
>>> I'm thinking it would be nicer to always have a field
>>> there for parsing.
>>
>> My gut feeling is to err on the side of being vague, like "unknown".
>> This is something that _shouldn't_ ever happen, and if it does, it could
>> be a broken on-disk ref, a transient syscall error, or some other
>> weirdness. I don't think we need to get too specific in this context
>> (we'll likely have said something else useful on stderr already, I
>> think).
>
> FWIW I think "unknown" is a nice conservative way to shrug Git's
> shoulders.
>
> When we call `git status --porcelain=v2` and read "unknown", we could
> always try to find out more using additional low-level tools and/or disk
> access: this is such a rare case that it does not *really* matter all that
> much.

yes, this case causes even rev-parse fits.  I'l make it return a
known quantity so that users don't have to deal with stuff like:

$ more .git/HEAD
ref: refs/heads/foo
$ more .git/refs/heads/foo
brokwn
$ git rev-parse HEAD
HEAD
fatal: ambiguous argument 'HEAD': unknown revision or path not in the 
working tree.
Use '--' to separate paths from revisions, like this:
'git <command> [<revision>...] -- [<file>...]'
$ git rev-parse HEAD --
fatal: bad revision 'HEAD'
$


Jeff