Github does it differently. They have "prod" stuff that everyone sees, and "candidate" things which are ALSO deployed from the same codebase (with different ena

Github does it differently. They have "prod" stuff that everyone sees, and "candidate" things which are ALSO deployed from the same codebase (with different enabling flags), and then can do long-term tests (and smaller pull requests) to verify that the New Way (candidate) behaves identically to the Old Way. Slide 35 [0] of this presentation actually starts the discussion of this exact thing, though Zach has talked about it before. Later, he shows a chart showing the differences as the code in the parallel branch changed over about five hours. (Wow, that's some fast iteration.) 0: https://speakerdeck.com/holman/move-fast-and-break-nothing?slide=35 https://speakerdeck.com/holman/move-fast-and-break-nothing?s...