evolve: remove the unnecessary condition to check empty successors set I annotated the history of this "newer == [()]" condition and found that it was added in the initial stages of evolution project (more than 8 years ago) and there is no test where we get [()] as a successor set. So looks like "if not newer" is enough to check if it is empty. I also looked into obsutil.successorssets() implementation and I don't think it would give us [()] in any case.