test_jobqueue: fix test_jobs_tuple()

this test was based on timing and assumed that the JobQueue did not have
time to start processing the queue before checking the assert.
what we really should do is make sure JobQueue does not process anything

tests/test_jobqueue.py

@@ -152,7 +152,7 @@ class JobQueueTest(BaseTest, unittest.TestCase):
         self.assertEqual(2, self.result)
 
     def test_jobs_tuple(self):
-
+        self.jq.stop()
         jobs = tuple(Job(self.job1, t) for t in range(5, 25))
 
         for job in jobs: