Jpeg thumbnailer & migration (4.3->4.4) process

[Jacopo De Simoi]

Dear devs,
  There's a patch at

http://reviewboard.kde.org/r/1444/

which makes the jpeg thumbnailer honor jpeg rotation infos stored in exif metadata. This means that with this patch, portrait and landscape jpeg photos will be thumbnailed and previewed accordingly (in dolphin, for instance).
However, in order to make this work properly, we need to "invalidate" jpeg thumbnails which have been previously created with the kioslave; 
the easiest way to accomplish this would be to erase all thumbnails (in ~/.thumbnails) created with the slave which point to a jpeg file, to force recreation of the thumbnail the next time the user browses the appropriate folder. 
I wonder if this is an allowed update migration procedure..
if so, what would be the right (tm) way to do that?
if not, what is an alternative acceptable solution?

Thanks
  --J