tomevault-io Rebase Branch onto Main
Rebase the current (or specified) branch onto main, correctly handling the case where the branch was built on top of another branch that has since been squash-merged into main.
Background
When a parent branch is squash-merged, its individual commits become a single new commit on main with a different hash. A normal git rebase main will try to replay the parent's original commits, causing messy conflicts. The fix is to cherry-pick only the commits unique to this branch onto a fresh branch from main.
Steps
Identify the branch. Use
$ARGUMENTSif provided, otherwise use the current branch.Fetch and update main:
git fetch origin main:mainFind the merge base between the branch and
main:git merge-base <branch> mainList all commits on the branch since the merge base:
git log --oneline <merge-base>..<branch>Identify which commits are unique to this branch vs. inherited from a parent branch. Look for:
- Squash-merged commits on
mainthat correspond to a group of commits at the bottom of the branch's history (check PR titles, commit message keywords). - The boundary commit: the first commit that belongs to this branch's work, not the parent's.
- If ALL commits are unique (no parent branch), just do a normal
git rebase mainand skip the rest.
- Squash-merged commits on
Create a fresh branch from
main:git checkout -b <branch>-rebase mainCherry-pick only the unique commits (oldest first):
git cherry-pick <first-unique-commit>^..<branch>The
A^..Brange means "from the parent of A through B inclusive."Handle conflicts if any arise during cherry-pick. Resolve and
git cherry-pick --continue.Replace the old branch:
git branch -m <branch> <branch>-old git branch -m <branch>-rebase <branch>Verify the result:
git log --oneline main..<branch>Confirm only the expected commits are present.
Ask the user before force-pushing. When approved:
git push origin <branch> --force-with-leaseClean up the old branch:
git branch -D <branch>-old
Source: PX4/PX4-Autopilot — distributed by TomeVault.