From: Mr Bill <billc56196@gmail.com>
Date: Tue, 06 May 2025 21:36:44 GMT
Subject: Bug report for pull --rebase
Message-ID: <8c075e6e-c28c-4146-66bc-9bd7bc705611@gmail.com>


Hi, I ran across this doing a pull --rebase using the current master 
version of git

This happens on Slackware linux, using git HEAD, version 2.35.8, and 2.46.2

I have a clone of the ffmpeg video package, with a few custom commits on 
top of it,
I periodically fetch and "pull --rebase" to update the underlying ffmpeg 
code.
I tried this recently, and my custom commits disappeared.


I looked further with a small test, and it looks like this is happening:

The setup:
    "base" repo with a few commits (A, B, C)
    "clone_1" cloned from "base", with a few extra commits (F, G)
    "clone_2" cloned from "clone_1"

Add a few more commits for base (D, E)

Then use "git remote set-url origin" to point "clone_2" to "base"

Then, in "clone_2" do "pull --rebase"; the F and G commits disappear.

Then, in "clone_1" do "pull --rebase"; the F and G commits are retained.

Something like this:

# commit trees:
#
#    base: A---B---C          (initial base repo with 3 commits)
# clone_1: A---B---C          (clone_1 cloned from base at commit C)
#    base: A---B---C---D---E  (base added extra commits D and E)
# clone_1: A---B---C---F---G  (clone_1 added extra commits F and G)
# clone_2: A---B---C---F---G  (clone_2 cloned from clone_1 at commit G)
#
# *** now, change clone_2 to use base as the upstream url, and fetch / 
pull / rebase to get up to date ***
#
# * set clone_2 upstream to point to base repo
# * "pull --rebase" in clone_2 (should fetch from base repo and rebase F 
and G after D and E)
#
#   expected result: A---B---C---D---E---F---G
#   actual result:   A---B---C---D---E
#   commits F and G are gone
#
# Doing "pull --rebase" in clone_1 gives the expected result:
#   expected result: A---B---C---D---E---F---G
#

This looks like either stale state info after the "set-url" command,
or I'm doing something wrong.

I can repeatedly cause this to happen in my local ffmpeg devel area, if 
that helps debug/test this.
... and answer questions, if any.

Thanks for the help!
Bill

P.S. here's the test script I used for this:

--------------------------------------------------------------------------

#!/bin/bash

set -o errexit

BASE_WORKING_DIR="rebase_bug.working"

# Clean up the test area
rm -rf "${BASE_WORKING_DIR:?}"
mkdir  "${BASE_WORKING_DIR:?}"
cd     "${BASE_WORKING_DIR:?}"

WORKING_DIR="${PWD}"

mkdir test_rebase_base.git
cd test_rebase_base.git

     # create the base git repo, with commit A, B and C
     git init
     echo "Commit A" > testfileA
     git add testfileA
     git commit -m "Commit A"

     echo "Commit B" > testfileB
     git add testfileB
     git commit -m "Commit B"

     echo "Commit C" > testfileC
     git add testfileC
     git commit -m "Commit C"

cd ..

     # Clone the base area into the clone_1 area
     git clone test_rebase_base.git test_rebase_clone_1.git

cd test_rebase_base.git
     # Add commit D and E to the base area

     echo "Commit D" > testfileD
     git add testfileD
     git commit -m "Commit D"

     echo "Commit E" > testfileE
     git add testfileE
     git commit -m "Commit E"

cd ..

cd test_rebase_clone_1.git
     # Add commit F and G to the clone_1 area

     echo "Commit F" > testfileF
     git add testfileF
     git commit -m "Commit F"

     echo "Commit G" > testfileG
     git add testfileG
     git commit -m "Commit G"

cd ..

     # clone from clone_1 into clone_2
     git clone test_rebase_clone_1.git test_rebase_clone_2.git

cd test_rebase_clone_2.git

     # change clone_2 to point to base

     git remote set-url origin "${WORKING_DIR:?}/test_rebase_base.git"

     # expecting this to pull in the "base" extra commits, and move the 
local HEAD commit after it in sequence
     git pull --rebase

cd ..

cd test_rebase_clone_1.git
     # do the same pull --rebase in clone_1
     git pull --rebase

cd ..

cd test_rebase_base.git
git log --oneline > "${WORKING_DIR:?}/test_rebase_base.oneline.log"
cd ..

cd test_rebase_clone_1.git
git log --oneline > "${WORKING_DIR:?}/test_rebase_clone_1.oneline.log"
cd ..

cd test_rebase_clone_2.git
git log --oneline > "${WORKING_DIR:?}/test_rebase_clone_2.oneline.log"
cd ..

# The test_rebase_clone_1.oneline.log and 
test_rebase_clone_2.oneline.log should match, but they don't

echo "done"

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