Forcing gerrit to regenerate a new review

Often in my work I have been asked how to detach a commit from an existing review in gerrit. The usual use-case is that somebody picked up some commit and then re-worked it significantly, making the original review, and review owner not applicable for follow-up.

Most regular git users will be confused because a git commit –amend will still end on the old review. The reason is that gerrit tracks changes not by commit hash but by metadata text called Change-Id. Think of it. If it did not have another mechanism besides the commit hash it would not know how to track a patchset review across rebases or amends

commit 71fbee6a7a41cbf8f59444fc48294e51c7cf9613 (HEAD)
Author: Paulo Neves <johny@gmail.com>
Date:   Mon Sep 6 14:07:14 2021 +0200

    My reworked stuff
    
    Change-Id: Ifdbfff8fbd8ee217b07b7b053c8927ae2a1126f0

Most people just manually change a random character in the Change-Id and this will lead to a unique Change-Id. Personally the way i do, given I often have hooks that automatically add the Change-Id, is to just edit the commit message to delete the line completely. A post-commit hook will just re-generate a new Change-Id line in the commit message and when i push it to gerrit a fresh review will be generated.