Re: bugreport: Wrong binary file content after cherry-pick

From: Junio C Hamano <gitster@pobox.com>
Date: May 13, 2020, 16:15 UTC
Message-ID: <xmqqsgg3vmiz.fsf@gitster.c.googlers.com>
In-Reply-To: <CAG2rzA=c8bGD6A_8kKCdz+UABjed9W6mSJYjLhYckbsXiFe4CQ@mail.gmail.com>

Chunlin Zhang <zhangchunlin@gmail.com> writes:

Show 25 quoted lines

> git version: after v2.21.0 can reproduce this bug
>
> reproduce steps:
> git clone https://github.com/zhangchunlin/gitbug
> cd gitbug
> git cherry-pick dev
>
> Then there will be a conflict with the cherry-pick, but if you run
> "md5sum *", will get:
> 6f96c8bc9e3df2f6fef1ecbb09f218f6
> ICS_usc_any_any_9.1.5_8871.uscc_261_130664_2048-release.apk
> 6f96c8bc9e3df2f6fef1ecbb09f218f6
> ICS_usc_any_any_9.8.0_b2cbd84d94.b2cbd84_297_131010_2048-release.apk
>
> The second file get a wrong file content.
> 3 related files md5:
> 6f96c8bc9e3df2f6fef1ecbb09f218f6
> ICS_usc_any_any_9.1.5_8871.uscc_261_130664_2048-release.apk
> d1bdd852b32c09ec93a5494afb3c67e7
> ICS_usc_any_any_9.1.5_8871.uscc_266_130703_2048-release.apk
> b2c50a9d7d488aa0b62ec7e68706ea85
> ICS_usc_any_any_9.8.0_b2cbd84d94.b2cbd84_297_131010_2048-release.apk
>
> I use git bisect to found the commit which cause this problem:
> https://github.com/git/git/commit/48c9cb9d6d058bcf18e931a1ed0d88792bb506c9

That's Elijah's 48c9cb9d (merge-recursive: improve rename/rename(1to2)/add[/add] handling, 2018-11-07)

The history Chunlin's repository has is a three-commit single strand of pearls; each commit's tree records only a single blob:

 * 'master' that has "uscc_261" file whose contents is f98ab07.

 * another commit on top of 'master' that renames "uscc_261" to
   "uscc_266" with some modifications; the contents after the
   modification is 3f71e11.

 * 'dev' that is a child of the above, which again renames it to a
   name without "uscc" in it, whose contents is 4f19f66.

As the .apk file is binary that cannot be merged textually, it is perfectly fine for "cherry-pick dev" to leave the index unmerged. The index has

    f98ab07 at uscc_261, stage #2 (ours)
    3f71e11 at uscc_266, stage #1 (common)
    4f19f66 at the name in 'dev', stage #3 (theirs)

which is perfectly expected.

In the working tree, we see

    "uscc_261" with contents f98ab07 (i.e. "ours")
    a file with the name in 'dev', with contents f98ab07

The latter is unexpected to me.