You don't ever push straight to the repo. You enqueue your changeset to be pushed by a central system. At Facebook we call this "asynchronous landing" and you're right, before this became a thing about five years back, at certain times of day it was very tricky to push your changes out.

Once you switch to this model, you can do convenient things like landing straight from the review system (by a "Ship it" button), landing after some checks were successfully performed, and so on.

Incidentally, this is similar to how merging pull requests by rebasing works on GitHub.