Fixed MultiTool test case

Updated the test case to match the change introduced in
085af4bb31d6a8049061649bb179231777a1ad9b.

celery/tests/bin/test_multi.py

@@ -176,15 +176,15 @@ class test_MultiTool(AppCase):
         self.assertFalse(self.fh.getvalue())
 
     def test_error(self):
-        self.t.say = Mock()
+        self.t.carp = Mock()
         self.t.usage = Mock()
         self.assertEqual(self.t.error('foo'), 1)
-        self.t.say.assert_called_with('foo')
+        self.t.carp.assert_called_with('foo')
         self.t.usage.assert_called_with()
 
-        self.t.say = Mock()
+        self.t.carp = Mock()
         self.assertEqual(self.t.error(), 1)
-        self.assertFalse(self.t.say.called)
+        self.assertFalse(self.t.carp.called)
 
         self.assertEqual(self.t.retcode, 1)