The owner should reject incoming reference messages

It should actually simply reject any message which does not match its configuration, i.e. in the case of a replication reference message it would be rejected because what the replication configuration indicates in the case of the owner can only be one of:

• send only FULL (already covered)
• send only REFERENCE (already covered)
• send/receive FULL (to be fixed)

and none of that is compatible with a received REFERENCE message.