How to get back <git fetch upstream; git merge upstream / master?

Question

This question differs from other questions in that I want to keep some commits while I return some commits.

Here is my setup.

Upstream repo on github (public repo which I don't own) Personal repo on my server(git clone --bare $upstream) 

My workflow was like this:

 Need to customize my personal branch 1. check out origin/master(Personal) 2. make changes 3. push to origin/master Need to get new feature or bug fix from the original author(github) 1. git fetch upstream 2. git merge upstream/master 

Now I find that upstream / master has an error and wants to return,
How can I return to the state before the last time I receive / combine upstream?

Change

Let's pretend that

• I leaked upstream
• I combined what the team member clicked on the source / master (personal)

Now I want to cancel step 1.

git reset --hard commit_sha_of_one_prior_the_merge_1

(Although searching for sha is not easy. Git log shows a lot of sha commit upstream, so it's not easy to find commit-sha-of_one_prior_the_merge_1, which is not from upstream , but from origin/master )

How to save the merge of step 2?

Assume a slightly more complex scenario

• I leaked upstream
• I combined what another member of the team clicked on Personal
• I also pushed my work to personal

Now I want to cancel the upward merge. How can i do this?

Answer 1

Since you have the actual merge - because you are introducing your own changes, you should be able to:

 git reset --hard HEAD~1 

Assuming your last commit was committed by merge.

Answer 2

You can reset the local branch of master to the state of origin/master (if you don't click merge on origin/master ) with:

 git reset --hard origin/master 

If this is not possible, you can use reflog:

 git reflog 

You can see undo git rebase for more details