Re: "fatal error in commit_refs" from pushing to github

> On Thu, Sep 08, 2016 at 07:49:12AM +0700, Duy Nguyen wrote:
>
>> I got the message in the subject when pushing to github today. Yes I
>> know it's github, not git. But according to stackoveflow [1] it's a
>> local problem. Which makes me think, if we know exactly what this is
>> (or at least roughly the problem area), maybe we could improve git to
>> catch it locally in the first place (and because other git servers may
>> not have the same protection as github).  Jeff maybe you can reveal
>> something about this "fatal error in commit_refs"? I'm sure it's not
>> in git code. But I would understand if the answer is "no".
>
> The short answer is that it's nothing to do with Git or the client; it's
> GitHub-specific code running on the server that is outside of Git
> entirely.
>
> The long answer is that pushes to GitHub don't hit Git directly these
> days. They hit a proxy layer that speaks just enough of the Git protocol
> to relay to N separate receives spread across N replica servers[1]. Those
> receive-packs take in the pack and verify it, but don't actually update
> any refs[2]. Then the proxy layer runs its own set of policy hooks, and
> speaks a commit-protocol to each of the replicas so that they all agree
> on the new ref state. That last step is called "commit_refs" internally.
>
> So this is really an internal failure at the ref-update stage. There
> _should_ be a reasonable error message, but I think "fatal error in
> commit_refs" is the generic last-ditch fallback. I'll pass this along to
> people in charge of that code, as we should be generating a more useful
> error message.