entity_get_all_property_info() sometimes won't get nested properties

I got an headache trying to understand why Search API interface does not allow me to index the "description" part of my file field.
Actually _search_api_wrapper_add_all_properties() uses entity_get_all_property_info() to retrieve all indexable properties for a given entity type.
But entity_get_all_property_info() does this:

  foreach ($info['bundles'] as $bundle => $bundle_info) {
    $bundle_info += array('properties' => array());
    $info['properties'] += $bundle_info['properties'];
  }

This means that for a given field, only the field's property info from the field instance of the first bundle will be retrieved. I have checked the file description property of my file field only for some bundles, and not for the first. Thus this property is not detected by Search API and I can't index it.
Here's a way to have it work, but I don't know if it might break things elsewhere:

  foreach ($info['bundles'] as $bundle => $bundle_info) {
    $bundle_info += array('properties' => array());
    $info['properties'] += $bundle_info['properties'];

    foreach ($bundle_info['properties'] as $name => $property) {
      if (isset($property['property info'])) {
        $info['properties'][$name]['property info'] += $property['property info'];
      }
    }
  }