Finding the right feature to cut during an 11th hour rush to shipping in a trick, and a meta-problem that can be result in amazingly rewarding (and time saving) hacks. Code of Honor has a great post on a pathfinding hack to get StarCraft out on time.

TL;DR: They removed collision between harvester units to avoid pathfinding failures. A great hack that causes no gameplay problem, and makes the whole system simpler to manage.