댓글을 하나 추출할때 댓글 번호가 없으면 null 리턴

git-svn-id: http://xe-core.googlecode.com/svn/sandbox@2518 201d5d3c-b55e-5fd7-737f-ddc643e51545

modules/comment/comment.model.php

@@ -35,6 +35,7 @@
          * @brief 댓글 가져오기
          **/
         function getComment($comment_srl, $is_admin = false) {
+            if(!$comment_srl) return;
             $args->comment_srl = $comment_srl;
             $output = executeQuery('comment.getComment', $args);
             $comment = $output->data;