message: [XLA:Python] Fix mishandling of multiple kwargs to traceme.
diff: @@ -545,11 +545,16 @@ class TraceMeContextManager {
  void Enter() {
  if (IsEnabled()) {
  std::string name(name_);
  - if (!kwargs_.empty()) {
  + // TODO(skye): we can use kwargs_.empty() once we upgrade to pybind11 2.4
  + // in workspace.bzl
  + if (kwargs_.size() != 0) {
  absl::StrAppend(&name, "#");
  + bool first = true;
  for (const auto& entry : kwargs_) {
  - absl::StrAppend(&name, std::string(py::str(entry.first)), "=",
  + absl::StrAppend(&name, first ? "" : ",",
  + std::string(py::str(entry.first)), "=",
  std::string(py::str(entry.second)));
  + first = false;
  }
  absl::StrAppend(&name, "#");
  }
  