fix _create_table_optimize_block

Author: jacquesqiao

python/paddle/fluid/distribute_transpiler.py

@@ -453,8 +453,7 @@ def __append_optimize_op__(op, block):
         if self.has_distributed_lookup_table:
             pserver_index = self.pserver_endpoints.index(endpoint)
             table_opt_block = self._create_table_optimize_block(
-                pserver_index, pserver_program, opt_state_block or
-                pserver_program.global_block())
+                pserver_index, pserver_program, pre_block_idx)
             prefetch_block = self._create_prefetch_block(
                 pserver_index, pserver_program, table_opt_block)
 
@@ -665,7 +664,7 @@ def _create_prefetch_block(self, pserver_index, pserver_program,
         return prefetch_block
 
     def _create_table_optimize_block(self, pserver_index, pserver_program,
-                                     append_block):
+                                     pre_block_idx):
         def _clone_var(block, var, persistable=True):
             assert isinstance(var, Variable)
             return block.create_var(
@@ -702,7 +701,7 @@ def _clone_var(block, var, persistable=True):
             op for op in self.optimize_ops
             if op.input("Param")[0] == self.table_name
         ][0]
-        table_opt_block = pserver_program.create_block(append_block.idx)
+        table_opt_block = pserver_program.create_block(pre_block_idx)
         # only support sgd now
         assert table_opt_op.type == "sgd"