Polling results with the amqp backend was not working properly

celery/backends/amqp.py

@@ -115,8 +115,6 @@ class AMQPBackend(BaseDictBackend):
         return result
 
     def get_task_meta(self, task_id, cache=True):
-        if cache and task_id in self._cache:
-            return self._cache[task_id]
         return self.poll(task_id)
 
     def wait_for(self, task_id, timeout=None, cache=True, propagate=True,
@@ -147,9 +145,13 @@ class AMQPBackend(BaseDictBackend):
         try:
             binding = self._create_binding(task_id)(channel)
             binding.declare()
-            result = binding.get()
-            if result:
-                payload = self._cache[task_id] = result.payload
+            latest, acc = None, None
+            while 1:  # fetch the last state
+                latest, acc = acc, binding.get(no_ack=True)
+                if not acc:
+                    break
+            if latest:
+                payload = self._cache[task_id] = latest.payload
                 return payload
             elif task_id in self._cache:  # use previously received state.
                 return self._cache[task_id]