Last modified: 2012-08-16 16:06:40 UTC
This is just an information: Please recognize that on Commons, when this error is detected in UpWiz, a button allowing to post an "undeletion request" is added. This bug is just for your information. You can mark as fixed as soon as the persons responsible have read it. A feature request for easier integration of "community tools" (sorry this is an illusion, there are only a few who write JS and even fewer who are experienced) will be filled.
With the last update of the API, Upload Wizard now shows a descriptive message (http://commons.wikimedia.org/wiki/File:2012-08-16_Upload_Wizard_duplicate-archive-error.png) and this part of the script was removed from Commons.
Great! With this in hand, I'll run around similar bugs and see if the problem persists for them as well. It may be there are warnings we aren't handling yet. Thanks very much for reporting back!