rewind: obsolete latest successors unless instructed otherwise To prevent the creations of divergence, we automatically mark the successors set of the rewinded changeset as obsoleted by the rewind result. A new flag `--as-divergence` is added to disable this behavior.

rewind: test rewinding an amended changesets We are now able to rewind a simple amended changeset. For now, its current successors has not been obsoleted and we created divergence.