Fix test breaking on Linux

celery/tests/test_log.py

@@ -34,6 +34,8 @@ class TestLog(unittest.TestCase):
         return self.assertFalse(val, reason)
 
     def test_setup_logger(self):
+        logger = setup_logger(loglevel=logging.ERROR, logfile=None)
+        logger.handlers = [] # Reset previously set logger.
         logger = setup_logger(loglevel=logging.ERROR, logfile=None)
         self.assertTrue(logger.handlers[0].stream is sys.stderr,
                 "setup_logger logs to stderr without logfile argument.")