'join' is what we have to use to wait for threads

(this has been broken for years)

xpra/server/background_worker.py

@@ -1,6 +1,6 @@
 # -*- coding: utf-8 -*-
 # This file is part of Xpra.
-# Copyright (C) 2013, 2014 Antoine Martin <antoine@xpra.org>
+# Copyright (C) 2013-2022 Antoine Martin <antoine@xpra.org>
 # Xpra is released under the terms of the GNU GPL v2, or, at your option, any
 # later version. See the file COPYING for details.
 
@@ -28,7 +28,7 @@ def __init__(self):
         self.daemon_work_items = WeakSet()
 
     def __repr__(self):
-        return "Worker_Thread(items=%s, exit=%s)" % (self.items.qsize(), self.exit)
+        return f"Worker_Thread(items={self.items.qsize()}, exit={self.exit})"
 
     def stop(self, force=False):
         if self.exit:

xpra/server/server_core.py

@@ -340,7 +340,7 @@ def quit_timer():
             if w and w.is_alive():
                 #wait up to 1 second for the worker thread to exit
                 try:
-                    w.wait(1)
+                    w.join(1)
                 except Exception:
                     pass
                 if w.is_alive():