Reset timeout loop of worker on each iteration

If there was a next task planned very soon, this should not become the default
timeout for future loop.

issue11913
review415971003
(grafted from 10426538d63f736318c9eb5028cf34d423701422)

--HG--
branch : 6.0

trytond/trytond/worker.py

@@ -62,15 +62,15 @@ def work(options):
     queues = [Queue(name, mpool) for name in options.database_names]
 
     tasks = TaskList()
-    timeout = options.timeout
     try:
         while True:
+            timeout = options.timeout
             while len(tasks.filter()) >= processes:
                 time.sleep(0.1)
             for queue in queues:
                 task_id, next_ = queue.pull(options.name)
-                timeout = min(
-                    next_ or options.timeout, timeout, options.timeout)
+                if next_ is not None:
+                    timeout = min(next_, timeout)
                 if task_id:
                     tasks.append(queue.run(task_id))
                     break