image converter doesn't care about revision
if you have an image item with multiple (different) revisions and you go to its history view, you can "show" or "download" each revision of it.
problem: "show" always shows the current revision of the image, because it does not include the revno in the img src url.
"download" works correctly and uses the correct url.
other converters should also be checked whether they process the correct revision.