GGG Cc: bug, was Re: [PATCH] pull: avoid running both merge and rebase

[Johannes Schindelin <Johannes.Schindelin@gmx.de>]

Hi Elijah,

On Sat, 28 Mar 2020, Elijah Newren wrote:

> On Sat, Mar 28, 2020 at 8:56 AM Jeff King <peff@peff.net> wrote:
> >
> > On Fri, Mar 27, 2020 at 09:51:40PM +0000, Elijah Newren via GitGitGadget wrote:
> >
> > > When opt_rebase is true, we still first check if we can fast-forward.
> > > If the branch is fast-forwardable, then we can avoid the rebase and just
> > > use merge to do the fast-forward logic.  However, when commit a6d7eb2c7a
> > > ("pull: optionally rebase submodules (remote submodule changes only)",
> > > 2017-06-23) added the ability to rebase submodules it accidentally
> > > caused us to run BOTH a merge and a rebase.  Add a flag to avoid doing
> > > both.
> > >
> > > This was found when a user had both pull.rebase and rebase.autosquash
> > > set to true.  In such a case, the running of both merge and rebase would
> > > cause ORIG_HEAD to be updated twice (and match HEAD at the end instead
> > > of the commit before the rebase started), against expectation.
> > >
> > > Signed-off-by: Elijah Newren <newren@gmail.com>
> > > ---
> > >     pull: avoid running both merge and rebase
> > >
> > >     Cc: Norbert Kiesel nkiesel@gmail.com [nkiesel@gmail.com], Jeff King
> > >     peff@peff.net [peff@peff.net]
> >
> > I'm not sure how cc is supposed to work with GGG, but it clearly didn't
> > here. :)
>
> Yeah, I clearly don't either.  I even looked up another submission
> from Dscho (https://github.com/git/git/pull/728) and attempted to
> mimic it, but still managed to get it wrong somehow and I don't know
> how.

It might be a bug in the way I implemented folding the cover letter into
single-patch mails. I simply might not pick up the Cc:s there.

However, I am seriously under water right now and won't be able to work on
a fix for that. Would you mind opening a ticket at
https://github.com/gitgitgadget/gitgitgadget/issues/new?

Thanks,
Dscho

>
> > Anyway, the patch looks good. Thanks for following through on this.
> >
> > > @@ -992,10 +993,12 @@ int cmd_pull(int argc, const char **argv, const char *prefix)
> > >                       if (is_descendant_of(merge_head, list)) {
> > >                               /* we can fast-forward this without invoking rebase */
> > >                               opt_ff = "--ff-only";
> > > +                             ran_ff = 1;
> > >                               ret = run_merge();
> > >                       }
> > >               }
> > > -             ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
> > > +             if (!ran_ff)
> > > +                     ret = run_rebase(&curr_head, merge_heads.oid, &rebase_fork_point);
> >
> > It feels like there should be some arrangement of the conditionals that
> > doesn't require setting an extra flag, but I actually don't think there
> > is. And anyway, doing the most obvious and minimal fix here is the right
> > place to start. We don't need more regressions. ;)
>
> Thanks for reviewing it.
>