cover fallback

oml/item/models.py

@@ -837,13 +837,13 @@ def update_sort_table():
 
 def download_cover(id):
     key = 'cover:%s' % id
+    cover = None
     with db.session():
         i = Item.get(id)
         if i:
             url = i.meta.get('cover')
         else:
             url = None
-            cover = None
 
     logger.debug('download cover %s %s', id, url)
     ratio = None