tensorflow: tf.Graph.get_tensor_by_name does not work as expected in TF2

System information

• Have I written custom code: yes
• OS Platform and Distribution: Max OSX 10.15.3 (Catalina)
• Mobile device: N/A
• TensorFlow installed from (source or binary): source
• TensorFlow version: v2.1.0-rc2-17-ge5bf8de410 2.1.0
• Python version: 3.7.6
• Bazel version (if compiling from source): N/A
• GCC/Compiler version (if compiling from source): N/A
• CUDA/cuDNN version: - GPU model and memory: N/A

Describe the current behavior tf.Graph.get_tensor_by_name returns ‘resource’ dtype tensors, which do not evaluate as expected in a session. For example, the code below will return something like:

array([( 10,), ( 44,), ( 47,), (106,), (111,), ( 98,), ( 58,), (108,),
       (111,), ( 99,), ( 97,), (108,), (104,), (111,), (115,), (116,),
       ( 47,), (114,), (101,), (112,), (108,), (105,), ( 99,), ( 97,),
       ( 58,), ( 48,), ( 47,), (116,), ( 97,), (115,), (107,), ( 58,),
       ( 48,), ( 47,), (100,), (101,), (118,), (105,), ( 99,), (101,),
       ( 58,), ( 67,), ( 80,), ( 85,), ( 58,), ( 48,), ( 18,), (  9,),
       (108,), (111,), ( 99,), ( 97,), (108,), (104,), (111,), (115,),
       (116,), ( 26,), (  1,), (120,), ( 32,), (224,), (167,), (192,),
       (135,), ( 18,), ( 42,), ( 18,), ( 78,), ( 49,), ( 48,), (116,),
       (101,), (110,), (115,), (111,), (114,), (102,), (108,), (111,),
       (119,), ( 51,), ( 86,), ( 97,), (114,), ( 69,), ( 50,), (  4,),
       (  8,), (  3,), ( 18,), (  0,)], dtype=[('resource', 'u1')])

Describe the expected behavior Expect v1 compatible code to work as it does in TF1.X. In particular, the code below should return 3.

Standalone code to reproduce the issue

import tensorflow.compat.v1 as tf
tf.disable_eager_execution()
x = tf.Variable(3, name='x')
y = tf.get_default_graph().get_tensor_by_name('x:0')
with tf.Session() as sess:
  sess.run(y)

Other info / logs

• When instantiating a tf.Variable:

WARNING:tensorflow:From /Users/shermes/Projects/tensorflow/venv2/lib/python3.7/site-packages/tensorflow_core/python/ops/resource_variable_ops.py:1635: calling BaseResourceVariable.__init__ (from tensorflow.python.ops.resource_variable_ops) with constraint is deprecated and will be removed in a future version.
Instructions for updating:
If using Keras pass *_constraint arguments to layers.

• From sess.run block:

/Users/shermes/Projects/tensorflow/venv2/lib/python3.7/site-packages/tensorflow_core/python/client/session.py:1445: FutureWarning: Passing (type, 1) or '1type' as a synonym of type is deprecated; in a future version of numpy, it will be understood as (type, (1,)) / '(1,)type'.

(This error shows up when using numpy 1.16 as well as 1.17 and 1.18.)