code: func ValidatePodStatusUpdate(newPod, oldPod *api.Pod) field.ErrorList {
  	allErrs := ValidateObjectMetaUpdate(&newPod.ObjectMeta, &oldPod.ObjectMeta, field.NewPath("metadata"))
  
  	// TODO: allow change when bindings are properly decoupled from pods
  	if newPod.Spec.NodeName != oldPod.Spec.NodeName {
  		allErrs = append(allErrs, field.Forbidden(field.NewPath("status", "nodeName"), "may not be changed directly"))
  	}
  
  	// For status update we ignore changes to pod spec.
  	newPod.Spec = oldPod.Spec
  
  	return allErrs
  }
docs: // ValidatePodStatusUpdate tests to see if the update is legal for an end user to make. newPod is updated with fields
  // that cannot be changed.