pytest: fix flake in test_gossip_pruning

We actually pruned before we got all the channels.  Extend the pruning time,
which unfortunately makes the test slower.

```
2024-11-18T02:13:11.7013278Z node_factory = <pyln.testing.utils.NodeFactory object at 0x7ff72969e820>
2024-11-18T02:13:11.7014386Z bitcoind = <pyln.testing.utils.BitcoinD object at 0x7ff72968fe20>
2024-11-18T02:13:11.7014996Z 
2024-11-18T02:13:11.7015271Z     def test_gossip_pruning(node_factory, bitcoind):
2024-11-18T02:13:11.7016222Z         """ Create channel and see it being updated in time before pruning
2024-11-18T02:13:11.7017037Z         """
2024-11-18T02:13:11.7017871Z         l1, l2, l3 = node_factory.get_nodes(3, opts={'dev-fast-gossip-prune': None,
2024-11-18T02:13:11.7018971Z                                                      'allow_bad_gossip': True})
2024-11-18T02:13:11.7019634Z     
2024-11-18T02:13:11.7020236Z         l1.rpc.connect(l2.info['id'], 'localhost', l2.port)
2024-11-18T02:13:11.7021153Z         l2.rpc.connect(l3.info['id'], 'localhost', l3.port)
2024-11-18T02:13:11.7021806Z     
2024-11-18T02:13:11.7022226Z         scid1, _ = l1.fundchannel(l2, 10**6)
2024-11-18T02:13:11.7022886Z         scid2, _ = l2.fundchannel(l3, 10**6)
2024-11-18T02:13:11.7023458Z     
2024-11-18T02:13:11.7023907Z         mine_funding_to_announce(bitcoind, [l1, l2, l3])
2024-11-18T02:13:11.7025183Z         l1_initial_cupdate_timestamp = only_one(l1.rpc.listchannels(source=l1.info['id'])['channels'])['last_update']
2024-11-18T02:13:11.7026179Z     
2024-11-18T02:13:11.7027358Z         # Get timestamps of initial updates, so we can ensure they change.
2024-11-18T02:13:11.7028171Z         # Channels should be activated locally
2024-11-18T02:13:11.7029326Z >       wait_for(lambda: [c['active'] for c in l1.rpc.listchannels()['channels']] == [True] * 4)
```

We can see in logs, it actually started pruning already:

```
2024-11-18T02:13:11.9622477Z lightningd-1 2024-11-18T01:52:03.570Z DEBUG   gossipd: Pruning channel 105x1x0 from network view (ages 1731894723 and 0)
```

Signed-off-by: Rusty Russell <[email protected]>

Author: rustyrussell

common/gossip_constants.h

@@ -82,7 +82,7 @@ enum query_option_flags {
  *     - MAY ignore the channel.
  */
 #define GOSSIP_PRUNE_INTERVAL(dev_fast_gossip_prune_flag) \
-	DEV_FAST_GOSSIP(dev_fast_gossip_prune_flag, 60, 1209600)
+	DEV_FAST_GOSSIP(dev_fast_gossip_prune_flag, 120, 1209600)
 
 /* How long after seeing lockin until we announce the channel. */
 #define GOSSIP_ANNOUNCE_DELAY(dev_fast_gossip_flag) \

lightningd/options.c

@@ -860,7 +860,7 @@ static void dev_register_opts(struct lightningd *ld)
 	clnopt_noarg("--dev-fast-gossip-prune", OPT_DEV,
 		     opt_set_bool,
 		     &ld->dev_fast_gossip_prune,
-		     "Make gossip pruning 30 seconds");
+		     "Make gossip pruning 120 seconds");
 	clnopt_witharg("--dev-gossip-time", OPT_DEV|OPT_SHOWINT,
 		       opt_set_u32, opt_show_u32,
 		       &ld->dev_gossip_time,

tests/test_gossip.py

@@ -47,10 +47,10 @@ def test_gossip_pruning(node_factory, bitcoind):
     wait_for(lambda: [c['active'] for c in l2.rpc.listchannels()['channels']] == [True] * 4)
     wait_for(lambda: [c['active'] for c in l3.rpc.listchannels()['channels']] == [True] * 4)
 
-    # All of them should send a keepalive message (after 30 seconds)
+    # All of them should send a keepalive message (after 120-30 seconds)
     l1.daemon.wait_for_logs([
         'Sending keepalive channel_update for {}'.format(scid1),
-    ], timeout=50)
+    ], timeout=100)
     l2.daemon.wait_for_logs([
         'Sending keepalive channel_update for {}'.format(scid1),
         'Sending keepalive channel_update for {}'.format(scid2),
@@ -66,9 +66,9 @@ def test_gossip_pruning(node_factory, bitcoind):
     # Now kill l2, so that l1 and l3 will prune from their view after 60 seconds
     l2.stop()
 
-    # We check every 60/4 seconds, and takes 60 seconds since last update.
+    # We check every 120/4 seconds, and takes 120 seconds since last update.
     l1.daemon.wait_for_log("Pruning channel {} from network view".format(scid2),
-                           timeout=80)
+                           timeout=150)
     l3.daemon.wait_for_log("Pruning channel {} from network view".format(scid1))
 
     assert scid2 not in [c['short_channel_id'] for c in l1.rpc.listchannels()['channels']]
@@ -2310,10 +2310,10 @@ def test_gossip_force_broadcast_channel_msgs(node_factory, bitcoind):
                             '--hex',
                             '--network={}'.format(TEST_NETWORK),
                             '--max-messages={}'.format(7),
-                            '--timeout-after={}'.format(30),
+                            '--timeout-after={}'.format(120),
                             '{}@localhost:{}'.format(l1.info['id'], l1.port)],
                            check=True,
-                           timeout=30 + TIMEOUT, stdout=subprocess.PIPE).stdout.decode('utf-8').split()
+                           timeout=120 + TIMEOUT, stdout=subprocess.PIPE).stdout.decode('utf-8').split()
 
     tally = {key: 0 for key in types.values()}
     for l in lines: