pytest: fix gossipwith flake harder.

Even though we generally wait until a node has seen the gossip,
that doesn't mean that connectd has processed it!  This means when
we connect it may still send us "old" gossip.

So we set the OPT_GOSSIP_QUERIES bit, which means don't send until we
ask.  But now it sends us WIRE_QUERY_CHANNEL_RANGE, so everyone needs
to filter that out.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

contrib/pyln-testing/pyln/testing/utils.py

@@ -1133,6 +1133,7 @@ class LightningNode(object):
                                timeout=TIMEOUT,
                                stdout=subprocess.PIPE).stdout.strip()
         out = subprocess.run(['devtools/gossipwith',
+                              '--features=40',  # OPT_GOSSIP_QUERIES
                               '--timeout-after={}'.format(int(math.sqrt(TIMEOUT) + 1)),
                               '{}@localhost:{}'.format(self.info['id'],
                                                        self.port),