Locally git can't tell if the clock is in the future, unless it starts checking ntp servers or the like. However it's not its own business IMHO. As a collabora

Locally git can't tell if the clock is in the future, unless it starts checking ntp servers or the like. However it's not its own business IMHO. As a collaboration tool GitHub might refuse timestamps too much in the future, at least as an optional setting of the repository. If a coworker inadvertently moves the clock forward by an year when looking for the day of next new year eve, then makes a day worth of commits and pushes them, we'll have to delete those commits and make them again with the correct date.