message: Add a defensive comment about the TOCTOU race
diff: @@ -500,6 +500,12 @@ class PyFuncOp : public OpKernel {
  call.ins.push_back(ctx->input(i));
  }
  + // NOTE(mrry): There is a potential time-of-check-to-time-of-use race here.
  + // because it is possible that `Py_Finalize()` could be called in another
  + // thread between this check and the call to `PyGILState_Ensure()`, which
  + // will abort the process if `Py_Finalize()` has been called. A more robust
  + // solution would be welcome, but it is not obvious how to make this work
  + // using the current Python C API.
  OP_REQUIRES(
  ctx, Py_IsInitialized(),
  errors::FailedPrecondition("Python interpreter state is not initialized. "
  