Comment 3 for bug 1722799

Reading logs between a successful run on x86 and a failed run on s390x, it would appear that stp never sees the topology change on br0 as p2 is removed - this log message is missing from the s390x logs:

   br0: detected topology change.

so I suspect the fdb cache ends up hitting some sort of age timeout before it gets flushed, rather than being activity flushed as a result of the topology change.