Comment 6 for bug 1046687

Might be a bug. But the code looks good and it works OK on my machine (file is opened with "append" mode so if it is not there, it should be automatically created).
Are you sure the deleted image was coming from an online source and was not a local image? Please delete the existing banned.txt in ~/.config/variety, then run variety from terminal with "-v" option and give it a try again by deleting some non-local wallpaper - you should see an option "View at xxx" in the menu for the image. And if you can confirm it's misbehaving, please report it as a separate bug and we'll track it down.