How can I update a published file and maintain the same URL?

After saving an update of a published file on my desktop, it will automatically "synchronise" with the corresponding files at UbuntuOne (and it does). Problem is that the "new file", actually the updated file with the same name, is no longer published. Pressing the publish button results is a new URL. I now have to mail new URL's and change embedded links, as old URL will result in a failure to find the updated file (or indeed any file).

I am not sure if it is a bug or a design flaw (maybe intentional?), but it seems strange to me.