Comment 9 for bug 309778

sun-java6-jre: /usr/share/mime/packages/sun-java6-jre.xml
this file is at fault.

Quoting:
 <mime-type type="application/java-archive">
  <comment>Java Archive</comment>
  <glob pattern="*.jar"/>
 </mime-type>

Since this overrides the default fdo xml it decreases the hit accuracy (thus we get 40 in kmimetypefinder...) only the file extension matches up, while everything else indicates zip, so result is zip, since a file extension can be wrong at times.

How to proof:
- remove above quoted parts from the affected file
- sudo update-mime-database /usr/share/mime
- kbuildsycoca4
- kmimetypefinder jNetTool-0.4.0.jar
application/x-java-archive
(accuracy 100)