fix distribute_transpiler

python/paddle/fluid/transpiler/distribute_transpiler.py

@@ -177,6 +177,7 @@ class DistributeTranspiler:
                         dtype=table_grad_var.dtype)
                     for index in range(len(self.pserver_endpoints))
                 ]
+        return param_list, grad_list
 
     def _init_splited_vars(self, slice_var_up):
         # update these mappings for further transpile:
@@ -199,8 +200,8 @@ class DistributeTranspiler:
                 grad_list.append(g)
                 param_grad_set.add(g.name)
 
-        self._update_dist_lookup_table_vars(param_list, grad_list,
-                                            self.params_grads)
+        param_list, grad_list = self._update_dist_lookup_table_vars(
+            param_list, grad_list, self.params_grads)
 
         if slice_var_up:
             # when we slice var up into blocks, we will slice the var according to