System information

• **OS Platform and Distribution: Ubuntu 16.04
• TensorFlow installed from (source or binary): binary
• TensorFlow version (use command below): ('v1.2.0-rc2-21-g12f033d', '1.2.0')
• Python version: 2

import tensorflow as tf
with tf.device('/gpu:0'):
    x = tf.constant([1, 2, 3])
    print(x.device)
with tf.device(lambda op: '/gpu:0'):
    y = tf.constant([1, 2, 3])
    print(y.device)
G = tf.get_default_graph()
with G.colocate_with(y):
    with tf.device('/gpu:0'):
        z = tf.constant([1,2,3])
        print(z.device)

Outputs:

/device:GPU:0
/gpu:0
WARNING:tensorflow:Tried to colocate Const_2 with an op Const_1 that had a different device: /device:GPU:0 vs /gpu:0. Ignoring colocation property.
/device:GPU:0

When using device function, '/gpu:0' doesn't get translated to '/device:GPU:0'. This can lead to very confusing warning messages when used together with colocate.