default-nodes: check if the ports exist in rescan_om
Ports might not be ready in the node's port object manager yet. This race condition might cause the default node to never be set. Instead, we need to check if the ports exist in rescan_om because the changed signal was triggered from that object manager.
Fixes #153 (closed), #150 (closed) and #151 (closed)
Edited by Julian Bouzas