KDE4 associating the wrong MIME type with .jar files

[Claudio]

Binary package hint: kdebase-runtime

As reported in bug #309778 KDE associates .jar files with .zip files - so you can not run .jar files but only extract them.
The commands xdg-mime and gvfs-info both report "application/x-java-archive" which is correct but file and kmimetypefinder both report "application/zip" (kmimetypefinder also reports 'accuracy 40' - a little bit low?) - so it first seemed to me that KDE is using the MIME database from the file command where it should use the shared-mime-info database as GNOME does - but after trying the same with a Python script only the file command missreports "text/x-java charset=us-ascii" and xdg-mime, gvfs-info and kmimetypefinder all report the correct "text/x-python" (kmimetypefinder this time with accuracy of 100) - so it seems to be using the correct database but somehow reporting the wrong mimetype for .jar files.
Happens in intrepid with KDE 4.2 backports (4:4.2.0-0ubuntu1~intrepid2) and in daily actual jaunty (4:4.2.1-0ubuntu2).