p2p_disconnect_ban intermittent issue #26808

https://cirrus-ci.com/task/5426348117196800?logs=ci#L4502

 test  2022-12-17T13:12:20.699000Z TestFramework.utils (ERROR): wait_until() failed. Predicate: '''' 
                                           self.wait_until(lambda: sum(peer['version'] != 0 for peer in to_connection.getpeerinfo()) == to_num_peers)
                                   '''
 test  2022-12-17T13:12:20.699000Z TestFramework (ERROR): Assertion failed 
                                   Traceback (most recent call last):
                                     File "/tmp/cirrus-ci-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 134, in main
                                       self.run_test()
                                     File "/tmp/cirrus-ci-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/p2p_disconnect_ban.py", line 112, in run_test
                                       self.connect_nodes(0, 1)  # reconnect the node
                                     File "/tmp/cirrus-ci-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 608, in connect_nodes
                                       self.wait_until(lambda: sum(peer['version'] != 0 for peer in to_connection.getpeerinfo()) == to_num_peers)
                                     File "/tmp/cirrus-ci-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/test_framework/test_framework.py", line 732, in wait_until
                                       return wait_until_helper(test_function, timeout=timeout, timeout_factor=self.options.timeout_factor)
                                     File "/tmp/cirrus-ci-build/ci/scratch/build/bitcoin-x86_64-pc-linux-gnu/test/functional/test_framework/util.py", line 281, in wait_until_helper
                                       raise AssertionError("Predicate {} not true after {} seconds".format(predicate_source, timeout))
                                   AssertionError: Predicate ''''
                                           self.wait_until(lambda: sum(peer['version'] != 0 for peer in to_connection.getpeerinfo()) == to_num_peers)
                                   ''' not true after 2400.0 seconds

Seen again here: https://cirrus-ci.com/task/4957567806341120?logs=ci#L574.

self.log.info("disconnectnode: successfully disconnect node by address")
address1 = self.nodes[0].getpeerinfo()[0]['addr']
self.nodes[0].disconnectnode(address=address1)
self.wait_until(lambda: len(self.nodes[0].getpeerinfo()) == 1, timeout=10)
assert not [node for node in self.nodes[0].getpeerinfo() if node['addr'] == address1]

We call disconnectnode and check if it worked by getpeerinfo. Perhaps, internally is it updating the informations before really compliting the disconnection? So, when node0 call disconnectnode (to disconnect node1) we could check whether it really disconnected by checking getpeerinfo for node1?

E.g.: Here we first remove from m_nodes (so getpeerinfo won't return that node anymore) and then we do the rest:

 if (pnode->fDisconnect)
  {
      // remove from m_nodes
      m_nodes.erase(remove(m_nodes.begin(), m_nodes.end(), pnode), m_nodes.end());

      // release outbound grant (if any)
      pnode->grantOutbound.Release();

      // close socket and cleanup
      pnode->CloseSocketDisconnect();

      // hold in disconnected pool until all refs are released
      pnode->Release();
      m_nodes_disconnected.push_back(pnode);
  }