message: Fix a multi-gpu test failure.
  The test uses tf.constant as input to all_reduce in pure eager mode, however in eager mode tf.constant always creates host tensors regardless of the enclosing device scope. This leads to NCCL error.
diff: @@ -131,7 +131,7 @@ class ReplicaCtxAllReduceTest(test.TestCase, parameterized.TestCase):
  def fn():
  def replica_fn():
  - value = constant_op.constant(1.0)
  + value = array_ops.identity(1.0)
  reduced = strategy.extended._replica_ctx_all_reduce('SUM', value)
  return reduced
  @@ -152,7 +152,7 @@ class ReplicaCtxAllReduceTest(test.TestCase, parameterized.TestCase):
  def fn():
  def replica_fn():
  - value = (constant_op.constant(1.0), constant_op.constant(2.0))
  + value = (array_ops.identity(1.0), array_ops.identity(1.0))
  reduced = strategy.extended._replica_ctx_all_reduce('SUM', value)
  return reduced
  