pytest: check that --daemon still means we recognize our own children.

We create our children then fork, so we're not a parent.  I noticed this
because 'lightning-cli stop' takes a long time: this is because it tries to
wait for them and they don't respond.

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

tests/test_misc.py

@@ -659,6 +659,7 @@ def test_cli(node_factory):
     assert only_one(j['invoices'])['label'] == 'l"[]{}'
 
 
+@pytest.mark.xfail(strict=True)
 def test_daemon_option(node_factory):
     """
     Make sure --daemon at least vaguely works!
@@ -683,6 +684,10 @@ def test_daemon_option(node_factory):
                     '--lightning-dir={}'.format(l1.daemon.lightning_dir),
                     'stop'], check=True)
 
+    # It should not complain that subdaemons aren't children.
+    with open('{}/log-daemon'.format(l1.daemon.lightning_dir), 'r') as f:
+        assert 'No child process' not in f.read()
+
 
 @flaky
 @unittest.skipIf(not DEVELOPER, "needs DEVELOPER=1")