Wallpaper switch does not open

[fatbug]

When selecting "Wallpaper switch" ("Переключатель обоев" in russian locale) from taskbar icon menu no switch appears.

There is an error in console

```
ERROR: 2017-12-23 10:57:37,332: show_thumbs() 'Could not create thumbs window:'
Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/variety/PreferencesVarietyDialog.py", line 761, in show_thumbs
    folder = self.parent.get_folder_of_source(self.model_row_to_source(row))
  File "/usr/lib/python2.7/dist-packages/variety/VarietyWindow.py", line 548, in get_folder_of_source
    dlr = self.create_downloader(type, location)
  File "/usr/lib/python2.7/dist-packages/variety/VarietyWindow.py", line 529, in create_downloader
    raise Exception('No Smart user yet, not a problem')
Exception: No Smart user yet, not a problem
```

Bug can be temporarily fixed by deleting config folder `~/.config/variety`

[M L (ml88-deactivatedaccount)]

Confirmed, since update to Ubuntu 17.10 I get the same error.
The task bar icon appears, but right-click does nothing (tested in Gnome and Mate).

When starting variety from a terminal, ctrl-c does nothing anymore when the bug occurs. Otherwise it shuts the application down.

After purging variety and deleting ~/.config/variety, it works again after reinstalling, but after some time the bug reoccurs.

[James Lu (jlu5)]

The "no smart user yet" seems to be a red herring because VRTY.org is no longer available (see https://bugs.launchpad.net/variety/+bug/1635912). Can you run variety -v and attach ~/.config/variety/variety.log ?

[Launchpad Janitor (janitor)]

[Expired for Variety because there has been no activity for 60 days.]