I've had a look at the Rules of Golf book provided by the R&A and have found a "Definition" that interprets your situation. I quote extensively:

Rule 19.1 By Outside Agency

If a ball in motion is accidentally deflected or stopped by any outside agency, it is a rub of the green, no penalty is incurred and the ball shall be played as it lies except:

a. If a ball in motion after a stroke other than on the putting green comes to rest in or on any moving or animate outside agency, the player shall, through the green or in a hazard, drop the ball, or on the putting green place the ball, as near as possible to the spot where the outside agency was when the ball came to rest in or on it.

Penalty for Breach of Rule:

Match Play - Loss of hole.

Stroke Play - Two strokes.

So in plain golfers language the rule states, that the ball is to be played from where it originally entered or landed in the greenkeepers cart and not where it finished up. The penalty is loss of the hole in match play or two strokes in stroke play.

I hope this makes it all a bit clearer. Cheers, Boynie.