Here's another twist to that question. Before coming to work, your trip is scheduled for 7:58 minutes of flying. Duty day is not a factor here, lets say. When you show up and check in, it now shows a flight time day of 8:10. Dispatch has amended the times. Are you legal to start and finish that trip if it will take you over the 8 hours?
No, not legal to start so you can't do it.