Work Annoyance 1: Git Rebase

December 1, 2020

How many times the below thing happens to you?

1. You have created hotfix or patch branch in your work
2. You have pushed your commits to your work remote repo
3. There has been a update in master leaving your hotfix branch out-of-sync with master.
4. You will be forced to “Sync them”
5. Now is the question? git rebase or git merge?

Though, git rebase is the keyword everyone uses and your managers will force you to rebase without knowing consequences.

Simply, git rebase won’t work. Will explain you why. git rebase takes all the commits from your hotfix branch and applies on the new branch out of master as if that hotfix commit was never made.

It is like as if yourself

1. Takes all the changes in the first commit of hotfix branch and then applies the changes to the corresponding files manually via a code editor and then you commit them like usual in a new temp branch cut out of master.
2. You would repeat 1 for all the commits in your hotfix branch.
3. And then you would delete the old hotfix branch and rename the temp branch as your hotfix branch git rebase automates the above steps with optimisations. You can read about git rebase in here.

One thing you might have noticed that the old hotfix branch and new rebased hotfix branch are not the same, though their contents are. you can confirm them by git log. You will see the new datetimes and new hashids or commit ids compared to what you saw in the old hotfix.

So, now when you try to push the changes to hotfix branch, you will get an error similar to, “Updates were rejected because the tip of your current branch is behind its remote”.

This is completely understandable since both branches have different ids in their history and no commit in common except for the base commit out of master.

And a normal git push origin hotfix cannot force the remote repo to override its hotfix branch.

Most often, Your organization would have disabled force-push, which lets u overwrite the hotfix branch.

Only working option u have is git merge. git merge is a very simple command. It adds a merge commit on top of current hotfix in addition to resolving any conflicts. You can read about it in here.

Now, you can easily push the branch because you are pushing only a single commit on top of existing hotfix branch without changing old commit ids.

So local hotfix is same as remote hotfix but one additional commit in local hotfix. But both hotfixes share the same history except for that one additional commit. Thereby, Remote can fast-forward its remote branch.

TLDR; don’t use git rebase, if u have pushed your branch to remote. Always use git merge.

Originally published on HackerNoon.

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