update cover if shared via metadata

oml/item/models.py

@@ -357,6 +357,8 @@ class Item(db.Model):
                 user = state.user()
                 if record and user in self.users:
                     Changelog.record_ts(user, self.modified, 'edititem', self.id, record)
+                if 'cover' in record:
+                    self.update_icons()
 
     def extract_preview(self):
         path = self.get_path()