The --simplify-merges logic did not cull irrelevant parents from a
merge that is otherwise not interesting with respect to the paths
we are following.
This touches a fairly core part of the revision traversal
infrastructure; even though I think this change is correct, please
report immediately if you find any unintended side effect.
* jc/remove-treesame-parent-in-simplify-merges:
simplify-merges: drop merge from irrelevant side branch