message: Clear the decref cache after calls to py_func to ensure no leaks
diff: @@ -432,6 +432,9 @@ class PyFuncOp : public OpKernel {
  py_threadstate = PyGILState_Ensure();
  bool log_on_error;
  Status s = DoCallPyFunc(&call, &log_on_error);
  + // Sometimes py_funcs can be called without a session and leak memory. This
  + // ensures we clear the decref cache so this doesn't happen.
  + ClearDecrefCache();
  PyGILState_Release(py_threadstate);
  // Ensures that GIL is released even when !s.ok().
  