Merge of field value in field/field.default.inc causing CTools ranges to display incorrectly

This issue could be fixed in CTools or here and I'm not sure which is the correct place. To describe the issue:-

• Using CTools and Panels with a multi-valued field which is then given a starting point and length (offset & length) so you can display just a subset of the field. This is done in the field configution when setting up a field via Panels (add field, choose settings, continue, enter value under 'Skip the first x items')
• Theme the field through field.tpl.php or an override and loop through the $items array to render each item individually.
• When displaying not all the items show consistently

The reason for this is that CTools has the following function in ctools/plugins/content_types/entity_context/entity_field.inc on line 144. This is as follows:-

  if (isset($conf['delta_limit'])) {
    $offset = intval($conf['delta_offset']);
    $limit = !empty($conf['delta_limit']) ? $conf['delta_limit'] : NULL;
    $all_values = array_slice($all_values, $offset, $limit, TRUE);
  }

The $all_values keeps the keys in the final array which eventually passes through to the field rendering. When the function

field_default_view($entity_type, $entity, $field, $instance, $langcode, $items, $display)

is called in modules/field/field.default.inc, there is an array merge of arrays which contain strings and integers. The integers are reset (which makes them different from the CTools list). On line 231:

$addition[$field['field_name']] = array_merge($info, $elements);

Then in the file /field/field.module, the function template_preprocess_field(&$variables, $hook) does a check to match the two arrays created above (the CTools $all_values and the data coming back from field_default_view. This happens on line 1044:

  foreach ($element['#items'] as $delta => $item) {
    if (!empty($element[$delta])) {
      $variables['items'][$delta] = $element[$delta];
    }
  }

The issue is that the $element[$delta] has a different set of keys to the $element['#items']. The fix for this should be quite simple. Line 231 of field.default.inc needs to be:-

$addition[$field['field_name']] = $info + $elements;

I'm going to create a patch now - but this is my first for core, so I'm not 100% sure how to do this correctly. Apologies if I mess it up.