message: [Grappler] Fix LoopOptimizer RemoveDeadBranchesConstantFeed test (wrong index
  for bool tensor).
diff: @@ -1548,7 +1548,7 @@ versions {
  CHECK(protobuf::TextFormat::ParseFromString(gdef_ascii, &item.graph));
  item.fetch = {"Identity"};
  Tensor feed_tensor(DT_BOOL, {});
  - feed_tensor.flat<bool>()(1) = false;
  + feed_tensor.flat<bool>()(0) = false;
  item.feed.push_back({"Const_1", feed_tensor});
  auto tensors_expected = EvaluateNodes(item.graph, item.fetch);
  ASSERT_EQ(tensors_expected.size(), 1);
  