fix sort check

README

@@ -146,6 +146,8 @@ Now you can open pandora in your browser, the first user to sign up will become
 
 === Updating ===
 To update a pandora installation get the latest version from bzr by running
+  su pandora
+  cd /srv/pandora
    ./update.py
 
 this will update pandora/oxjs/python-ox and list possible upgrades to the db

pandora/item/models.py

@@ -361,10 +361,14 @@ class Item(models.Model):
         else:
             self.poster_height = 128
             self.poster_width = 80
-        if not settings.USE_IMDB and self.sort:
-            if self.poster_frame == -1 and self.sort.duration:
+        if not settings.USE_IMDB:
+            if self.poster_frame == -1:
+                try:
+                    if self.sort.duration:
                         self.poster_frame = self.sort.duration/2
                         update_poster = True
+                except ItemSort.DoesNotExist:
+                    pass
         self.json = self.get_json()
         self.json['modified'] = datetime.now()
         super(Item, self).save(*args, **kwargs)