Calendar events more then 1 Month in future --> "in %s Mon" (Language de)

Hawking

Hi,

I’m using the calender to show the next public holidays by including a public calendar:

               {
                    module: "calendar",
                    header: "Feiertage",
                    position: "top_left",
                    config: {
                            calendars: [
                                    {
                                            url: "http://www.ifeiertage.de/by-.ics"
                                    }
                            ]
                    }
            },

The appointments that are more than 1 Month away are just shown as “in %s Mon.”, see attached image.

Maybe the plural of “Mon.” has to be explicitly specified (I’m using language: de) but I don’t know how.
Can you reproduce (and maybe fix) this issue?