Re: BUG: fetch in certain repo always gives "did not send all necessary objects"

> On Tue, Feb 06, 2018 at 04:00:32PM -0800, Elijah Newren wrote:
>
>> It took me hours to figure it out, after users ran out of ideas and
>> came and asked me for help.  (Maybe if I was familiar with worktree,
>> and knew they had been using it, then I might have guessed that "HEAD"
>> meant "not your actual HEAD but the HEAD of the vestige of some other
>> worktree").
>
> Yeah, this is the obvious thing that seems like it ought to be improved.

> Unfortunately fixing that is a little tricky. In this case the stack
> looks like:
>
>   parse_object_or_die (oid=0x7fffffffd690, name=0x555555792880 "HEAD") at object.c:239
>   add_one_ref (path=0x555555792880 "HEAD", oid=0x7fffffffd690, flag=0, cb_data=0x7fffffffd8e0) at reachable.c:38
>   refs_head_ref (refs=0x555555a65430, fn=0x5555556b6ef5 <add_one_ref>, cb_data=0x7fffffffd8e0) at refs.c:1316
>   other_head_refs (fn=0x5555556b6ef5 <add_one_ref>, cb_data=0x7fffffffd8e0) at worktree.c:404
>
> So other_head_refs knows that it's looking at the worktrees. And it
> passes the alternate ref-store to refs_head_ref(), with "add_one_ref" as
> the callback. But the knowledge that we're not talking about the real
> "HEAD" is lost as we cross that callback boundary. We'd need to either
> add another parameter to the callback, or have some way of talking about
> "HEAD in this worktree" as a refname (which AFAIK we don't have).