Let me readily acknowledge that our process wasn't optimal. The CoffeeScript version-change happened while I was completely offline for a week, having dumped the next dev right in the middle of things with insufficient handover, so we caught that a bit late.

In hindsight (1) I should have used something other than Make for my build process and (2) I should have figured out a way to move some of the build upstream.

Things to get right next time.