Friday's 1.15.2 patch will break your save games. You will still be able to move to stable build and continue playing your games.
Tomorrow (Thursday) we will be upgrading Stable to 1.15.1. We will be creating a new branch labeled Legacy which will continue with 1.14.8 (current stable.)
Friday we will move Default to 1.15.2.
Make sense? If not post to this announcement or make a thread and I'll be happy to answer your questions. I'll post a how-to switch branches tomorrow when Stable gets upgraded.