The part that's unequivocally a bug, there were references to auxiliary_graphs we'd removed still left in support_graph attributes present on edges. These will now be removed if we removed the aux_graph they reference.
A matter of opinion. Previously, we removed an auxiliary_graph if any of the edges it contained contained blocked nodes. Now, we will remove these edges individually (potentially leaving a disconnected auxiliary_graph), and will only remove the auxiliary_graph itself if all of the edges it contains are removed.
Two major things were changed here: