Undo a merge by pull request

Question

Someone accepted a pull request which they shouldn t have  Now we have a bunch of broken code merged in  How do you undo a pull request  I was just going to revert the changes to the commit just before the merge  but I noticed that it merged in a bunch of commits  So now there are all these commits from this person from days before the merge  How do you undo this

User · Accepted Answer

There is a better answer to this problem, though I could just break this down step-by-step.

You will need to fetch and checkout the latest upstream changes like so, e.g.:

git fetch upstream
git checkout upstream/master -b revert/john/foo_and_bar

Taking a look at the commit log, you should find something similar to this:

commit b76a5f1f5d3b323679e466a1a1d5f93c8828b269
Merge: 9271e6e a507888
Author: Tim Tom <[email protected]>
Date:   Mon Apr 29 06:12:38 2013 -0700

    Merge pull request #123 from john/foo_and_bar

    Add foo and bar

commit a507888e9fcc9e08b658c0b25414d1aeb1eef45e
Author: John Doe <[email protected]>
Date:   Mon Apr 29 12:13:29 2013 +0000

    Add bar

commit 470ee0f407198057d5cb1d6427bb8371eab6157e
Author: John Doe <[email protected]>
Date:   Mon Apr 29 10:29:10 2013 +0000

    Add foo

Now you want to revert the entire pull request with the ability to unrevert later. To do so, you will need to take the ID of the merge commit.

In the above example the merge commit is the top one where it says "Merged pull request #123...".

Do this to revert the both changes ("Add bar" and "Add foo") and you will end up with in one commit reverting the entire pull request which you can unrevert later on and keep the history of changes clean:

git revert -m 1 b76a5f1f5d3b323679e466a1a1d5f93c8828b269

User · Answer

Starting June 24th  2014  you can try cancel a PR easily  See  Reverting a pull request   with   Introducing the Revert Button     you can easily revert a pull request on GitHub by clicking Revert         You ll be prompted to create a new pull request with the reverted changes      It remains to be tested though if that revert uses -m or not  for reverting merges as well   But Adil H Raza adds in the comments  Dec  2019        That is the expected behavior  it created a new branch and you can create a PR from this new branch to your master    This way in the future you can un-revert the revert if need be  it is safest option and not directly changing your master      Warning  Korayem points out in the comments that      After a revert  let s say you did some further changes on Git branch and created a new PR from same source destination branch    You will find the PR showing only new changes  but nothing of what was there before reverting    Korayem refers us to  Github  Changes ignored after revert  git cherry-pick  git rebase   for more

User · Answer

If you give the following command you ll get the list of activities including commits  merges  git reflog Your last commit should probably be at  HEAD  0    You can check the same with your commit message  To go to that point  use the command git reset --hard  HEAD  0   Your merge will be reverted  If in case you have new files left  discard those changes from the merge

User · Answer

I use this place all the time  thanks   I was searching for how to undo a pull request and got here   I was about to just git reset --hard to  a long time ago  and do a fast forward back to where I was before doing the pull request   Besides looking here  I also asked my co-worker what he would do  and he had a typically good answer  using the example output in the first answer above   git reset --hard 9271e6e   As with most things in Git  if you re doing it some way that s not easy  you re probably doing it wrong

User · Answer

Look at your commit graph  with gitk or a similar program   You will see commits from the pull request  and you will see your own commits  and a merge commit  if it was not a fast-forward merge   You just have to find the last of your own commits before the merge  and reset the branch to this commit    If you have the branch s reflog  it should be even easier to find the commit before the merge       Edit after more information in comments    Okay  lets look at the graph     I assume the last  rightmost  commit was your wrong merge by pull request  which merged the blue line seen here  Your last good commit would be the one before on the black line  here marked in red     Reset to this commit  and you should be fine   This means  in your local working copy do this  after making sure you have no more uncommitted stuff  for example by git stash    git checkout master git reset --hard 7a62674ba3df0853c63539175197a16122a739ef gitk    Now confirm that you are really on the commit I marked there  and you will see none of the pulled stuff in its ancestry   git push -f origin master    if your github remote is named origin - else change the name    Now everything should look right on github  too  The commits will still be in your repository  but not reachable by any branch  thus should not do any harm there   And they will be still on RogerPaladin s repository  of course     There might be a Github specific web-only way of doing the same thing  but I m not too familiar with Github and its pull request managing system    Note that if anyone else already might have pulled your master with the wrong commit  they then have the same problem as you currently have  and can t really contribute back  before resetting to your new master version   If it is likely that this happened  or you simply want to avoid any problems  use the git revert command instead of git reset  to revert the changes with a new commit  instead of setting back to an older one   Some people think you should never do reset with published branches   See other answers to this question on how to do this   For the future   If you want only some of the commits of RogerPaladin s branch  consider using cherry-pick instead of merge  Or communicate to RogerPaladin to move them to a separate branch and send a new pull request

User · Answer

If the pull was the last thing he did then  git reset --hard HEAD 1

User · Answer

To undo a github pull request with commits throughout that you do not want to delete  you have to run a   git reset --hard --merge  lt commit hash gt   with the commit hash being the commit PRIOR to merging the pull request  This will remove all commits from the pull request without influencing any commits within the history   A good way to find this is to go to the now closed pull request and finding this field    Pull Request Image  After you run the git reset  run a   git push origin --force  lt branch name gt   This should revert the branch back before the pull request WITHOUT affecting any commits in the branch peppered into the commit history between commits from the pull request   EDIT   If you were to click the revert button on the pull request  this creates an additional commit on the branch  It DOES NOT uncommit or unmerge  This means that if you were to hit the revert button  you cannot open a new pull request to re-add all of this code

[git] Undo a merge by pull request?

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