Tests passing on Py2.6

celery/exceptions.py

@@ -78,7 +78,7 @@ class RetryTaskError(Exception):
         if self.message:
             return self.message
         if self.excs:
-            return 'Retry {0}: {!r}'.format(self.humanize(), self.excs)
+            return 'Retry {0}: {1!r}'.format(self.humanize(), self.excs)
         return 'Retry {0}'.format(self.humanize())
 
     def __reduce__(self):

celery/worker/control.py

@@ -99,7 +99,7 @@ def rate_limit(panel, task_name, rate_limit, **kwargs):
     try:
         timeutils.rate(rate_limit)
     except ValueError as exc:
-        return {'error': 'Invalid rate limit string: {!r}'.format(exc)}
+        return {'error': 'Invalid rate limit string: {0!r}'.format(exc)}
 
     try:
         panel.app.tasks[task_name].rate_limit = rate_limit