Re: [PATCH] clone: fix refspec on "--single-branch" option

From: Ralf Thielow <ralf.thielow@gmail.com>
Date: Sep 14, 2012, 14:25 UTC
Message-ID: <CAN0XMOJFG2_Ju8fcAcyTiUc3owjedpKX+LpHdBWdym36Hm0LdA@mail.gmail.com>
In-Reply-To: <CACsJy8BLwd=XeHFqg5jb=yx3p6xdKuzvG+KvfotfLf0vfSZdRQ@mail.gmail.com>

On Fri, Sep 14, 2012 at 3:10 PM, Nguyen Thai Ngoc Duy <pclouds@gmail.com> wrote:

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> On Fri, Sep 14, 2012 at 1:48 PM, Junio C Hamano <gitster@pobox.com> wrote:
>> Junio C Hamano <gitster@pobox.com> writes:
>>
>>> Who guarantees at this point in the codepath that option_branch is
>>> set when option_single_branch is non-zero?  Until we talk with the
>>> remote, "clone --single-branch" without an explicit "--branch" will
>>> not learn which branch at the remote we are going to fetch (it will
>>> be their HEAD).
>>>
>>> I wonder if this should be more like this:
>>>
>>>       if (option_single_branch) {
>>>               if (option_branch)
>>>                       Your patch "+refs/heads/foo:refs/remotes/origin/foo";
>>>               else
>>>                       "HEAD";
>>>         } else {
>>>               Original "+refs/heads/*:refs/remotes/origin/*";
>>>       }
>>>
>>> That is, "clone --single-branch" will continue fetching from and
>>> integrating with their HEAD without storing any remote tracking
>>> branch.
>>
>> Alternatively, if you can move the logic to set up this
>> configuration further down so that it happens after we talked to the
>> other side and figured out remote_head_points_at, you could instead
>> set it up to keep a single remote tracking branch.
>
> That sounds reasonable. I have a question though, what should a user
> do when he/she want to fetch all branches again? Messing up with
> refspec in config file is not something I would like to do.
>

$ git remote set-branches <remote> "*"

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> Perhaps a heuristic in git-fetch to detect "single branch" situation
> and ignore refspec? We could hint people that refspecs are not
> followed when remote has more than one branch. They could either fetch
> the another branch explicitly, which turns off the heuristic, or turn
> off the advice.
>

Such an advice when using "--single-branch" is a good idea, i think. Something like "The remote <remote> is configured to fetch only branch <branch>. If you want to fetch all branches, use "git remote set-branches <remote> "*"" or something like that.

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>> Even if you did so, guess_remote_head() may not find any branch when
>> the other repository's HEAD is detached, so you would need to decide
>> what to do in such a case, and "fetch and integrate their HEAD
>> without using any remote tracking branch" may be a reasonable thing
>> to do in such a case.
> --
> Duy