> When you have an ardent follower of "DRY" who refactors a common utility so that many subsystems of a distributed system have a code dependency on the same piece of code, then changing that piece of code can become very costly.

Is this a piece of code that actually requires co-ordinating all nodes so they're running the same version of the code? Otherwise I'm not sure I see the problem, since you can just run old versions of the shared code in parallel with new versions.