message: Preserve aliasing in copyToIpu
  Summary: Fixes T7221
  Test Plan:
  all tests pass apart from `//tensorflow/contrib/ipu:ops_test` which
  doesn't seem related.
  Reviewers: davidn, jakeh
  Maniphest Tasks: T7221
diff: @@ -343,9 +343,9 @@ StatusOr<poplar::program::Program> CreateInterIpuCopy(
  return xla::FailedPrecondition("No unique IPU number on %s", inst->name());
  }
  - out =
  - poputil::copyToIpu(res.main_graph, out, seq, sharding.GetUniqueDevice(),
  - GetDebugName(inst));
  + out = poputil::copyToIpu(
  + res.main_graph, out, seq, sharding.GetUniqueDevice(), GetDebugName(inst),
  + poplar::TensorCloneMethod::PRESERVE_ORDER_AND_ALIASES);
  TF_CHECK_OK(AddOutputTensor(tensor_map, inst, 0, out));
  return seq;
  