connectd: fix race when we supply a new address.

This shows up as a flake in test_route_by_old_scid:


```
        # Now restart l2, make sure it remembers the original!
        l2.restart()
>       l2.rpc.connect(l1.info['id'], 'localhost', l1.port)

tests/test_splicing.py:554: 
...
>           raise RpcError(method, payload, resp['error'])
E           pyln.client.lightning.RpcError: RPC call failed: method: connect, payload: {'id': '0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518', 'host': 'localhost', 'port': 33837}, error: {'code': 400, 'message': 'Unable to connect, no address known for peer'}
```

This is because it's already (auto)connecting, and fails.  This
failure is reported, before we've added the new address (once we add
the new address, we connect fine, but it's too late!):

```
lightningd-2 2025-12-08T02:39:18.241Z DEBUG   gossipd: REPLY WIRE_GOSSIPD_NEW_BLOCKHEIGHT_REPLY with 0 fds
lightningd-2 2025-12-08T02:39:18.320Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: Initializing important peer with 0 addresses
lightningd-2 2025-12-08T02:39:18.320Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: Failed connected out: Unable to connect, no address known for peer
lightningd-2 2025-12-08T02:39:18.344Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: Will try reconnect in 1 seconds
lightningd-2 2025-12-08T02:39:18.344Z DEBUG   035d2b1192dfba134e10e540875d366ebc8bc353d5aa766b80c090b39c3a5d885d-connectd: Initializing important peer with 1 addresses
lightningd-2 2025-12-08T02:39:18.344Z DEBUG   035d2b1192dfba134e10e540875d366ebc8bc353d5aa766b80c090b39c3a5d885d-connectd: Connected out, starting crypto
lightningd-2 2025-12-08T02:39:18.344Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: Adding 1 addresses to important peer
lightningd-2 2025-12-08T02:39:18.345Z DEBUG   0266e4598d1d3c415f572a8488830b60f7e744ed9235eb0b1ba93283b315c03518-connectd: Connected out, starting crypto
{'run_id': 256236335046680576, 'github_repository': 'ElementsProject/lightning', 'github_sha': '555f1ac461d151064aad6fc83b94a0290e2e9d5d', 'github_ref': 'refs/pull/8767/merge', 'github_ref_name': 'HEAD', 'github_run_id': 20013689862, 'github_head_ref': 'fixup-backfill-bug', 'github_run_number': 14774, 'github_base_ref': 'master', 'github_run_attempt': '1', 'testname': 'test_route_by_old_scid', 'start_time': 1765161493, 'end_time': 1765161558, 'outcome': 'fail'}
lightningd-2 2025-12-08T02:39:18.421Z DEBUG   022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59-hsmd: Got WIRE_HSMD_ECDH_REQ
lightningd-2 2025-12-08T02:39:18.421Z DEBUG   hsmd: Client: Received message 1 from client
lightningd-2 2025-12-08T02:39:18.453Z DEBUG   022d223620a359a47ff7f7ac447c85c46c923da53389221a0054c11c1e3ca31d59-hsmd: Got WIRE_HSMD_ECDH_REQ
lightningd-2 2025-12-08T02:39:18.453Z DEBUG   hsmd: Client: Received message 1 from client
--------------------------- Captured stdout teardown ---------------------------
```

Author: rustyrussell

lightningd/connect_control.c

@@ -277,10 +277,21 @@ static void connect_failed(struct lightningd *ld,
 					  connect_nsec,
 					  connect_attempted);
 
-	/* We can have multiple connect commands: fail them all */
-	while ((c = find_connect(ld, id)) != NULL) {
-		/* They delete themselves from list */
-		was_pending(command_fail(c->cmd, errcode, "%s", errmsg));
+	/* There's a race between autoreconnect and connect commands.  This
+	 * matters because the autoreconnect might have failed, but that was before
+	 * the connect_to_peer command gave connectd a new address.  This we wait for
+	 * one we explicitly asked for before failing.
+	 *
+	 * A similar pattern could occur with multiple connect commands, however connectd
+	 * does simply combine those, so we don't get a response per request, and it's a
+	 * very rare corner case (which, unlike the above, doesn't happen in CI!).
+	 */
+	if (strstarts(connect_reason, "connect command")) {
+		/* We can have multiple connect commands: fail them all */
+		while ((c = find_connect(ld, id)) != NULL) {
+			/* They delete themselves from list */
+			was_pending(command_fail(c->cmd, errcode, "%s", errmsg));
+		}
 	}
 }
 

tests/test_splicing.py

@@ -499,7 +499,6 @@ def test_splice_stuck_htlc(node_factory, bitcoind, executor):
     assert l1.db_query("SELECT count(*) as c FROM channeltxs;")[0]['c'] == 0
 
 
-@pytest.mark.flaky(reruns=5)
 @unittest.skipIf(TEST_NETWORK != 'regtest', 'elementsd doesnt yet support PSBT features we need')
 def test_route_by_old_scid(node_factory, bitcoind):
     l1, l2, l3 = node_factory.line_graph(3, wait_for_announce=True, opts={'experimental-splicing': None, 'may_reconnect': True})