fix code style

test=develop

python/paddle/fluid/layers/io.py

@@ -404,8 +404,8 @@ def open_recordio_file(filename,
 
     startup_var.desc.set_dtypes(dtypes)
     startup_var.persistable = True
-    main_prog_var = _copy_reader_var_(
-        default_main_program().current_block(), startup_var)
+    main_prog_var = _copy_reader_var_(default_main_program().current_block(),
+                                      startup_var)
 
     if pass_num > 1:
         main_prog_var = multi_pass(reader=main_prog_var, pass_num=pass_num)