changelog: add a changelog entry about divergence resolution We made a lots of progress there.

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.

tests: fix a test case to not create conflicts This is the test case where we are testing about divergence resolution of stack of patches. If the stack is as follows: C1 C2 | | B1 B2 | | A1 A2 \/ base And A1-A2, B1-B2 and C1-C2 are content-divergent, and merging A1-A2 results in conflicts. Now if you resolve conflicts and continue resoling B1-B2, the conflicts of A1-A2 will still be there. We need somehow to understand the work we has done and not create conflicts again. To test the evolution functionality for now, we make sure conflicts does not occur.