Multiple ops Dequeue ops from the same queue started getting optimized away in latest TensorFlow:

The following executes dequeue once in Jan17 head, but 3 times in 12.1
sess.run([q.dequeue(), q.dequeue(), q.dequeue()])

One gets expected behavior (3 dequeues) when graph optimization is turned off

tf.ConfigProto(graph_options=tf.GraphOptions(optimizer_options=tf.OptimizerOptions(opt_level=tf.OptimizerOptions.L0)))
sess = tf.Session(config = config)

Self-contained repro: https://github.com/yaroslavvb/stuff/blob/master/parallel_dequeue_test.py

Came up in http://stackoverflow.com/questions/41830206/how-to-share-a-queue-containing-variable-length-sequences-batches-between-multip