Comment 6 for bug 344228

Making a copy of the image is a lot cheaper than adding a hack to Nautilus which it runs when an image gets deleted ;)

I'm confirming this one, if nobody minds. Even I (and I consider myself reasonably knowledgeable) feel pretty overwhelmed when it comes to adding wallpapers, because I know that if I move or rename the image I will lose my beautiful catalogue of wallpapers! Thus, I usually make a copy into a special folder anyway. It is tremendously annoying (and kind of saddening) when wallpapers just disappear, since I spend lots of time collecting them and setting the appropriate styles. Further, it is currently impossible to set a remote image as a wallpaper since there is no convention in place for where the image should be placed.
People who aren't aware of the details involved are bound to encounter issues at some point, as described here.

A very simple fix could resolve the issue.