I can't call the chronometer not working a "game breaking" bug as there's a million ways to find target speed. "Game breaking" is when you can't for whatever reason accomplish the tasks set out before you in the game.
Ah well. I'm happy to have a patch. Some people will never be satisfied. An Ubisoft rep could show up on their doorstep with a bottle of champagne and 10 girls in bikinis, and they'd complain that the booze wasn't cold enough and the girls weren't hot enough.