D-Bus testing: fix race condition in TestLocalSync.testNoParent

The first progress signal gets emitted after sleeping for 10 seconds
at the start of the sync and then killing syncevo-dbus-server races
with completing the sync. What we want is to kill during the 10 second
wait, so we better wait for the debug output directly before it and
then kill directly.

test/test-dbus.py

@@ -4583,25 +4583,20 @@ END:VCARD''')
             DBusUtil.pserver.wait()
             DBusUtil.pserver = None
             loop.quit()
-            # Remove timeout by returning false.
-            self.killTimeout = None
-            return False
-        def progressChanged(*args, **keywords):
-            # Now give sync some more time to get started. Less than
-            # the 10 seconds that the child process gets delayed,
-            # enough to get it started.
-            delay = 1
-            logging.printf('killing syncevo-dbus-server in %d seconds', delay)
-            self.killTimeout = Timeout.addTimeout(delay, killServer)
-            # Don't call me again.
-            self.progressChanged = None
-        # Wait for first sign of a running sync.
-        self.progressChanged = progressChanged
-
-        self.session.Sync("slow", {})
-        loop.run()
-        if self.killTimeout is not None:
-            Timeout.removeTimeout(self.killTimeout)
+        def output(path, level, text, procname):
+            if self.running and DBusUtil.pserver and text == 'ready to sync':
+                killServer()
+        receiver = bus.add_signal_receiver(output,
+                                           'LogOutput',
+                                           'org.syncevolution.Server',
+                                           self.server.bus_name,
+                                           byte_arrays=True,
+                                           utf8_strings=True)
+        try:
+            self.session.Sync("slow", {})
+            loop.run()
+        finally:
+            receiver.remove()
 
         # Should have killed server.
         self.assertFalse(DBusUtil.pserver)