lollypop crashed with AttributeError
-### Environment
-- Lollypop version: 0.9.305 -- GTK+ version: 3.18.9 -- Operating system: Ubuntu 16.04 -- Nemo 3.6.4
-### Bug
Right-click on "Popular albums", "Loved Albums", "Recently added" etc. or simple click on "Popular tracks", "Loved tracks", "Recently played" (Playlists menu) etc. >> lollypop crashed with AttributeError in _on_button_press_event(): 'Popover' object has no attribute 'popup'
File "/usr/lib/python3.6/site-packages/lollypop/selectionlist.py", line 386, in _on_button_press_event popover.popup() AttributeError: 'Popover' object has no attribute 'popup'