The Update branch button on the pull request page lets you update your pull request's branch with the latest changes from the base branch. This is useful for verifying your changes are compatible with the current version of the base branch before you merge. Two enhancements now give you more ways to keep your branch up-to-date.
Update your pull request branch by rebasing
When your pull request's branch is out of date with the base branch, you now have the option to update it by rebasing on the latest version of the base branch. Rebasing applies the changes from your branch onto the latest version of the base branch, resulting in a branch with a linear history since no merge commit is created.
To update by rebasing, click the drop down menu next to the Update Branch button, click Update with rebase, and then click Rebase branch.
Previously, Update branch performed a traditional merge that always resulted in a merge commit in your pull request branch. This option is still available, but now you have the choice.
Note: Because rebasing rewrites the history of the branch, if you are working with the branch locally, you will need to fetch it and do a hard reset to ensure your local branch matches the branch on GitHub.com.
Learn more about keeping your pull request in sync with the base branch.
Always have the option to update
A new repository setting lets admins opt into having the Update branch button always available whenever a pull request's branch is not up to date with the base branch. Previously, this button was only available when the Require branches to be up to date before merging branch protection setting was enabled.
Repository admins and maintainers can manage the Always suggest updating pull request branches setting from the Pull Requests section in repository settings.
Learn more about managing suggestions to update pull request branches.