Re: 2.37.2 can't "git pull" but 2.18.0 can

>
> On Thu, Sep 08, 2022 at 12:46:14PM -0400, Lana Deere wrote:
>
> > With an explicit -c protocol.version=0 on the 2.37.2 git command line,
> > the pull is successful.  For what it's worth, the server git is still
> > 2.18.0 in all of these cases.  Only the client side is being tested so
> > far.  I will try to gather the packet traces and see if there's a
> > problem sharing them.  Will this mailing list allow attachments?
>
> You can send attachments to the list as long as the total mail size is
> under 100kb. But to keep the list in the loop: Lana sent me the traces
> off-list, because naturally they have a bunch of semi-private ref names.
>
> I was able to see the problem from the traces: the v2 protocol has an
> extension to tell the server to limit the advertisement only to branches
> we're interested in. And it does so based on the configured refspec. As
> Dscho noted earlier in the thread, the upstream branch you want isn't in
> the refspec. We try to add that branch explicitly to what we're
> fetching, but I think that happens too late to affect the ref-prefix
> limiting. So the server is asked not to advertise the ref, and from the
> client's perspective, it looks like the branch does not exist on the
> server.
>
> Here's a minimal reproduction:
>
>   # a server with two branches
>   git init server
>   (
>     cd server
>     git checkout -b branch1
>     git commit --allow-empty -m foo
>     git branch branch2
>   )
>
>   # and a client which points its origin there,
>   # and has local copies of both branches, tracking
>   # the upstream versions
>   git clone server client
>   cd client
>   git checkout branch1
>   git checkout branch2
>
>   # but afterwards, the client narrows its refspec to only fetch branch1
>   git config remote.origin.fetch +refs/heads/branch1:refs/remotes/origin/branch1
>
>   # pulling branch2 with v0 works
>   git -c protocol.version=0 pull
>
>   # but does not with v2, because the ref-prefix extension tells the
>   # server not to advertise anything outside of branch1
>   git -c protocol.version=2 pull
>
> This is a bug which we should fix. But in the meantime the obvious
> workaround is to expand the default refspec to cover both branches.
> Obviously the default of fetching "refs/heads/*" would work, but if you
> want to keep it limited for some reason, you can add the second branch
> explicitly. In the example above, it would be:
>
>   git config --add remote.origin.fetch +refs/heads/branch2:refs/remotes/origin/branch2
>
> -Peff