You can imagine how big of a surprise was finding out that model/character being a child of model/node causes an error when we import model/position.

Basically, the idea is that a train tried to start with the caboose brakes stuck on. After releasing the caboose, the train still could not start. The problem was that when the train attempted to start with the caboose brake on, it stretched all the inter-car couplings so that the whole train was just like one big car. At this point, the friction from the engine train wheels was not enough to get the whole thing going. Instead, you need to just get one car moving at a time - this is why there is space between the couplings.

Capybara and Webrat use some of the same method names which leads to runtime collisions that reveal themselves in confusing ways.