Page History

...

A critical thing to point out is that you need must submit a new version of the entire patch - not just an update to the patch.

The easiest way to update the most recent commit (which is often the one you want to update), is to use "git commit --amend -a".  This will "add" any modifications in the current repository and merge them into the last commit.  If there are no changes, or "-a" is not used, it will only editing this will just allow you to edit the most recent commit commentmessage.  This is useful if you don't have a Change-Id: line in your commit message (because you didn't install the commit-msg hook, see Commit Comments above), but one was added automatically by Gerrit.  You can copy the Change-Id: line from the Gerrit web page for that change and paste it into the amended commit message.  Typically, the updated patch should also be rebased to the tip of the current branch before pushing it again, to ensure that it does not conflict with other changes that may have been landed since the patch was first developed.

...