GossipSub messages relayed back to source on 3 node network

[cskiraly]

Setting up a 3 node network (nodes A,B,C) and a single GS topic. When A is sending a message to B and C, these are then relayed between them, finally sent back to A. That last step is not supposed to happen, since on that link the same message already travelled and was received.

Message sequence A->B , A->C B->C, C->B C->A, B->A