message: test: Fix rpc_net.py "pong" race condition
  Prior to this change, the test fails with KeyError if pong has
  a zero value at the time this is called, as getpeerinfo's
  bytesrecv_per_msg result excludes zero-values.
diff: @@ -67,8 +67,8 @@ class NetTest(BitcoinTestFramework):
  peer_info_after_ping = self.nodes[0].getpeerinfo()
  for before, after in zip(peer_info, peer_info_after_ping):
  - assert_greater_than_or_equal(after['bytesrecv_per_msg']['pong'], before['bytesrecv_per_msg']['pong'] + 32)
  - assert_greater_than_or_equal(after['bytessent_per_msg']['ping'], before['bytessent_per_msg']['ping'] + 32)
  + assert_greater_than_or_equal(after['bytesrecv_per_msg'].get('pong', 0), before['bytesrecv_per_msg'].get('pong', 0) + 32)
  + assert_greater_than_or_equal(after['bytessent_per_msg'].get('ping', 0), before['bytessent_per_msg'].get('ping', 0) + 32)
  def _test_getnetworkinginfo(self):
  assert_equal(self.nodes[0].getnetworkinfo()['networkactive'], True)
  