Comment 3 for bug 1737445

I'm really sorry but I have failed to re-create the bug on my own system. As I didn't discover the problem for at least a month, I can't remember exactly when it occurred or what I did to make it happen. I do remember that after the first attempt to upgrade, there was a problem with using the "revert" button on the Software Sources application, which re-enabled all the Artful sources even though I hadn't upgraded - so I had to manually alter the /etc/apt/sources.list to go back to Zesty. I'm pretty sure that I would have enabled all the Zesty sources including updates, as the sources.list is not that complicated.

However I can't tell you how this happened, so regrettably I think I have to withdraw the bug report (or at least ask you to do so). I apologise for wasting your time on this one.