Add a kluge to handle pushes to branches with exactly one commit When pushing to a branch, githelper checks if the old head of the branch is reachable from the new head following only first-parents. As an optimization, no more first-parents are followed once the old head has been reached, which is to say old^ and its ancestors are excluded from the rev-list. However, if old does not have a parent, then rev-list fails to interpret old^. So as a kluge, detect this case and disable the optimization as needed...