Imagine if someone clicks the deploy button when you're in the middle of typing something and then the service goes down due to a syntax error. To prevent this, we will need some sort of way to set a global lock to indicate that "I'm not done typing yet" and you can only deploy once everyone has released this lock.
Or you don't deploy unless it makes it through at least testing, and a build started while someone was editing the code would probably fail fast unless you coincidentally hit the button right when it's valid, but wrong, code.
