obsolete-parent: evolve the case when parent has multiple successors Before this patch, we were used to return error that parent has multiple successors and exit. This patch take more care of that case and if obsolete parent's successors are: 1) split successors, then we check if they are on a single topological branch we update to tipmost, otherwise we ask user to select. 2) divergent successors, we suggest user to `hg update` to one of the successors and run `hg evolve --content-div` to resolve the problem. Changes in test file shows the updated behavior.