Excerpt won't be shown when searching single CJK word alone

Problem/Motivation

I'm now using the latest stable version of search_api ( 7.x-1.12 ) on Drupal 7.28 and found that the result of searching with single CJK keyword ( like Japanese "ユーザ" ) doesn't show any excerpt while searching with English words works perfectly. My processors settings of search index are quite simple where the HTML filter and highlighting are enable. ( see the attached image )

Proposed resolution

In the constructor of SearchApiHighlight class declared in processor_highlight.inc, $split is defined like this.

    self::$split = '/[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . $cjk . ']+/iu';

Then, this variable is used to split search keywords in getKeywords function as follows:

  protected function getKeywords(SearchApiQuery $query) {
    $keys = $query->getKeys();
    if (!$keys) {
      return array();
    }
    if (is_array($keys)) {
      return $this->flattenKeysArray($keys);
    }

    $keywords = preg_split(self::$split, $keys);
:

So, every time I use single CJK word in searching, preg_split used here returns empty array since $split covers all CJK ranges. I think $split should not cover and its definition should be as follows removing "$cjk" concatination

    self::$split = '/[' . PREG_CLASS_UNICODE_WORD_BOUNDARY . ']+/iu';

So far, this fix works fine for me and if you need more information about my environment, kindly let me know.