I guess no solution, so I just hack the module.
/public_html/testserver/the-exaple.com/sites/all/modules/contrib/quiz/question_types/short_answer
public function evaluateAnswer($user_answer) {
...
switch ($this->node->correct_answer_evaluation) {
case self::ANSWER_MATCH:
if ($user_answer == $this->node->correct_answer) {
$score = $this->node->max_score;
}
break;
case self::ANSWER_INSENSITIVE_MATCH:
////////////////edit your code here
break;
case self::ANSWER_REGEX:
if (preg_match($this->node->correct_answer, $user_answer) > 0) {
$score = $this->node->max_score;
}
break;
}
...
}
Since I chose my answer is insensitive, I will edit second case.