Reviews are required, but we don't have automation to test integrity and authenticity. Mostly the diffs between what is reviewed and what is pushed are cosmetics that the reviewer asked for and pre-r+'ed without wanting another patch in a bug, but there's room for mischief.

People do watch bugs and repos and catch stuff. We are working on making the system more foolproof, as part of a larger effort to move all our CI infra (save Mac, sigh) to the cloud and our release engineering to a devops model.