Re: [PATCH] t3424: new rebase testcase documenting a stat-dirty-like failure

>
> Hi Elijah
>
> On 18/02/2020 15:59, Elijah Newren wrote:
> > On Tue, Feb 18, 2020 at 7:05 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
> >>
> >> Hi Elijah
> >>
> >> On 17/02/2020 19:12, Elijah Newren wrote:
> >>> I forgot to add some cc's in GitGitGadget before submitting; adding now...
> >>>
> >>> On Mon, Feb 17, 2020 at 9:15 AM Elijah Newren via GitGitGadget
> >>> <gitgitgadget@gmail.com> wrote:
> >>>>
> >>>> From: Elijah Newren <newren@gmail.com>
> >>>>
> >>>> A user discovered a case where they had a stack of 20 simple commits to
> >>>> rebase, and the rebase would succeed in picking the first commit and
> >>>> then error out with a pair of "Could not execute the todo command" and
> >>>> "Your local changes to the following files would be overwritten by
> >>>> merge" messages.
> >>>>
> >>>> Their steps actually made use of the -i flag, but I switched it over to
> >>>> -m to make it simpler to trigger the bug.  With that flag, it bisects
> >>>> back to commit 68aa495b590d (rebase: implement --merge via the
> >>>> interactive machinery, 2018-12-11), but that's misleading.  If you
> >>>> change the -m flag to --keep-empty, then the problem persists and will
> >>>> bisect back to 356ee4659bb5 (sequencer: try to commit without forking
> >>>> 'git commit', 2017-11-24)
> >>>>
> >>>> After playing with the testcase for a bit, I discovered that added
> >>>> --exec "sleep 1" to the command line makes the rebase succeed, making me
> >>>> suspect there is some kind of discard and reloading of caches that lead
> >>>> us to believe that something is stat dirty, but I didn't succeed in
> >>>> digging any further than that.
>
> I think `--exec true` would be better as it makes it clear that it's not
> a timing issue. I've changed do_recursive_merge() to print the mtime and
> mode of "DS" before and after the merge which gives
>
> HEAD is now at abd8fe3 side1
> Rebasing (1/2) # picking commit1
> DS mtime, mode before merge 1582109854, 120000
> DS mtime, mode after merge 0, 120000
> Rebasing (2/2) # picking commit2
> DS mtime, mode before merge 0, 120000
> error: Your local changes to the following files would be overwritten by
> merge:
>         DS
>
> So it looks like the problem is that when we pick commit1 we don't
> update the index entry for DS properly in merge_trees()
>
> Best Wishes
>
> Phillip