git command for making one branch like another

Question

I\'m trying to take a branch with changes and bring it back to be identical to the upstream it diverged from. The changes are both local and have been pushed to github, so n

Answer 1

Heavy handed, but hell, what can possibly go wrong?

• Check out the branch X you want to look like the Y
• cp -r .git /tmp
• Check out branch Y git checkout y
• rm -rf .git && cp -r /tmp/.git .
• Commit & push any difference
• DONE.

Answer 2

Another simulation for git merge -s theirs ref-to-be-merged:

git merge --no-ff -s ours ref-to-be-merged         # enforce a merge commit; content is still wrong
git reset --hard HEAD^2; git reset --soft HEAD@{1} # fix the content
git commit --amend

An alternative to the double reset would be applying the reverse patch:

git diff --binary ref-to-be-merged | git apply -R --index

Answer 3

Use git reset BACKWARDS!

You can make a branch look like any other commit with git reset, but you have to do it in a round-about way.

To make a branch on commit <old> look like a commit <new>, you can do

git reset --hard <new>

in order to make <new> the contents of the working tree.

Then do

git reset --mixed <old> 

to change the branch back to the original commit but leaving working tree in the <new> state.

Then you can add and commit the changes, in order to make your branch exactly match the contents of the <new> commit.

It's counter-intuitive that to move from the <old> state to the <new> you need to do a git reset from <new> to <old>. However with the option --mixed the working tree is left at <new> and the branch pointer set to <old>, so that when the changes are committed the branch looks how we want.

Warning

Don't lose track of your commits, e.g. forget what <old> is when doing git reset --hard <new>.