message: Make transpose + matmul fusion idempotent.
diff: @@ -919,8 +919,9 @@ string ArithmeticOptimizer::TrySimplifyAndReplaceUses(
  }
  // Fold Transpose into matrix multiplication.
  - if (node->op() == "MatMul" || node->op() == "SparseMatMul" ||
  - node->op() == "BatchMatMul") {
  + if ((node->op() == "MatMul" || node->op() == "SparseMatMul" ||
  + node->op() == "BatchMatMul") &&
  + node_map->GetNode(node->name() + "_fused") == nullptr) {
  const NodeDef* a = node_map->GetNode(node->input(0));
  const NodeDef* b = node_map->GetNode(node->input(1));
  bool is_complex = false;
  