Temp workaround for critical pickle trackers lt bug

deluge/core/torrentmanager.py

@@ -575,6 +575,11 @@ class TorrentManager(component.Component):
             else:
                 paused = False
 
+            # XXX: Temporary workaround for critical bug with RC_1_1 lt code.
+            # remove this code when lt 1.2 is released.
+            for tracker in torrent.trackers:
+                tracker.pop('last_error', None)
+
             torrent_state = TorrentState(
                 torrent.torrent_id,
                 torrent.filename,