Use is_resource_variable() in train.assert_gloabl_step.

PiperOrigin-RevId: 190573872

tensorflow/python/training/training_util.py

@@ -18,7 +18,6 @@
 from __future__ import division
 from __future__ import print_function
 
-
 from tensorflow.python.eager import context
 from tensorflow.python.framework import dtypes
 from tensorflow.python.framework import graph_io
@@ -31,7 +30,6 @@
 from tensorflow.python.platform import tf_logging as logging
 from tensorflow.python.util.tf_export import tf_export
 
-
 # Picked a long key value to minimize the chance of collision with user defined
 # collection keys.
 GLOBAL_STEP_READ_KEY = 'global_step_read_op_cache'
@@ -170,8 +168,7 @@ def assert_global_step(global_step_tensor):
   """
   if not (isinstance(global_step_tensor, variables.Variable) or
           isinstance(global_step_tensor, ops.Tensor) or
-          isinstance(global_step_tensor,
-                     resource_variable_ops.ResourceVariable)):
+          resource_variable_ops.is_resource_variable(global_step_tensor)):
     raise TypeError(
         'Existing "global_step" must be a Variable or Tensor: %s.' %
         global_step_tensor)