bug: rendezvous unsubscribed peer is discoverable

[AlejandroCabeza]

Problem

After some iterations of running advertise/unsubscribe on RendezVous, the unsubscribe doesn't make the peer non-discoverable.

To reproduce

1. Instantiate some switches (peerA, peerB), both using RendezVous.
2. Connect them.
3. Advertise peerA in namespace N.
4. From peerB, request a peer in namespace N.
5. Repeat steps 3 and 4 until a peerA is discovered.

• The first couple of times doing this, the request will fail as no peers will be found. After some iterations, peerA will be discoverable.

Alternatively, you can checkout the tests/gossipsub/peer-discovery branch, open tests/testdiscovery.nim and run the Frequent sub/unsub test case.

Expected behavior

After unsubscribing, the unsubscribed peer shouldn't be discoverable.

Versions

Nim: 2.0.8
PR: #1168