For example, I just merged master branch to my feature branch. Then someone pushed new stuff on master. So I merged again to keep up. And then someone pushed again... I merge again. How do I squash the previous merges so that two merge actions is combined to one?
How can I turn this:
o---o---A---B---C---D---E
\ \ \ \
F---G---H---I---J
into this:
o---o---A---B---C---D---E
\ \
F---G-----------J'
where J and J' contain exactly the same codes.
This method prevents the need to re-resolve merge-conflicts by re-playing the previously-resolved changes into the merge commit.
git checkout feature
git diff master > feature.patch
git reset --hard G
git branch --move trimmed_feature
git checkout -b feature master
git merge --strategy ours trimmed_feature --no-edit
git apply feature.patch --index
git commit --amend --message "Merge branch 'master' into feature"
git branch -D trimmed_feature
We first remove the old merges to create a trimmed feature branch, then create a clean feature branch from master, merge in our trimmed feature branch using git merge --strategy ours to ignore the changes, then re-apply the previously-resolved changes from the patch.