Allow additional rule actions for free shipping rule

The free shipping discount doesn't utilize pricing components. I have a project where I was evaluating pricing components to help track what discounts have been applied to line items, etc. So I attempted to work around this by adding a custom action to all of the free shipping rules. I had struggled with why my custom actions were not sticking until I located the culprit.

commerce_discount_commerce_discount_rule_build looks to find any discount offer that uses the commerce_free_shipping field so it can add the shipping service to the commerce_discount_free_shipping_service action. It does this by looping through all actions on the rule, however for each action that is not commerce_discount_free_shipping_service, it deletes it.

    // Add missing parameter.
    foreach ($rule->actions() as $action) {
      if ($action->getElementName() == 'commerce_discount_free_shipping_service') {
        $action->settings['shipping_service'] = $shipping_service;
      }
      else {
        $action->delete();
      }
    }

Is there a reason that every other action is deleted? I couldn't find anything that made this necessary so I've created a patch (coming shortly) to remove the $action->delete().