evolve: create resolved cset on successors of current parents While resolving content-divergence, sometimes, the parent can be obsolete and have a successor. We should consider the successors of the parents instead of obsolete parents as that will do something like orphan+content-divergence resolution both at the same time which is powerful and results in a single stack while resolving content-divergence of stacks. The test changes demonstrates that we can now successfully evolve a content divergent stack.