Unrelated code appears in cherrypick's PR

[Rustin170506]

Bug Report

• I have searched the issues of this repository and believe that this is not a duplicate.

Related link

• Which project: ticdc

• PR or Issue Link: https://github.com/pingcap/ticdc/pull/2181

Steps to reproduce(Optional)

I don't know how to reproduce it.

What is expected?

Do not add code that does not appear in the original PR.

What is actually happening?

https://github.com/pingcap/ticdc/pull/2181/files#diff-03f95b96b27da3637e3aa86c8c47fe140af8529f7c9c78aa34372a6f13ca9718

This file was not added to the original pr, but appears in cherry-pick's pr.

cc: @Mini256

[Mini256]

It seems that it is not a completely unrelated file, because it has been modified in the original pr:
https://github.com/pingcap/ticdc/pull/2172/files#diff-03f95b96b27da3637e3aa86c8c47fe140af8529f7c9c78aa34372a6f13ca9718

[Mini256]

It seems that your PR merged into the release-5.1 branch faster than the PR that added the file.

[Rustin170506]

It seems that your PR merged into the release-5.1 branch faster than the PR that added the file.

What do you mean?

[Mini256]

What do you mean?

This file is added to master by https://github.com/pingcap/ticdc/pull/1621, but it doesn't seem to be cherry-picked to release-5.1, Its pick PR has not been merged, https://github.com/pingcap/ticdc/pull/2130, So when you modify a file that doesn't exist in the release-5.1 branch, it becomes an add the file.

[Rustin170506]

What do you mean?

This file is added to master by pingcap/ticdc#1621, but it doesn't seem to be cherry-picked to release-5.1, Its pick PR has not been merged, pingcap/ticdc#2130, So when you modify a file that doesn't exist in the release-5.1 branch, it becomes an add the file.

Are you saying that when we apply a patch to a branch, if the file doesn't exist, it will just copy the file? Is it possible that we can try to reproduce this issue locally? Download the patch and apply it manually? if you don't have time I can try this weekend.

[Mini256]

mkdir gittest
cd gittest
git init
echo "file 1" > 1.txt
git add .
git commit -m "init commit"
git branch -v

git checkout -b release-5.1
git branch -v

git checkout master
echo "pr #1621" > 2.txt
git add .
git commit -m "pr 1621: add 2.txt file"
git log

git checkout -b yourbranch
echo "pr 2172" > 2.txt
git add .
git commit -m "pr 2172: update 2.txt file"
git log

git branch -v
git checkout master
git merge yourbranch
git log
git branch -v

git checkout release-5.1
ls    # only 1.txt in release-5.1 branch now
git cherry-pick f1683596d0b645c6bc1f3ba6badb045175e86e71
git add .
git commit -m "cherry-pick 2172"
git log

[Mini256]

@hi-rustin, Do you have any questions about this Issue?

[Rustin170506]

Thanks for your help in reproducing the issue! Can you try the GitHub patch? Also does this behavior need to be written into the documentation?