Quoted email not stripped when adding comments in German Outlook format

In Outlook-formatted emails, the current mail is separated from quoted mails by:

---Ursprüngliche Nachricht---

(or some variant), and the user can choose to strip all content below this line. In JIRA <= 3.3.1 this isn't working for the German (and other non-English) separators. The whole mail gets appended as a comment.