find and cards with invalid dids on deck list

anki/decks.py

@@ -368,6 +368,13 @@ class DeckManager(object):
         return self.col.db.list("select id from cards where did in "+
                                 ids2str(dids))
 
+    def recoverOrphans(self):
+        dids = self.decks.keys()
+        mod = self.col.db.mod
+        self.col.db.execute("update cards set did = 1 where did not in "+
+                            ids2str(dids))
+        self.col.db.mod = mod
+
     # Deck selection
     #############################################################
 

anki/sched.py

@@ -176,6 +176,7 @@ order by due""" % self._deckLimit(),
         self._checkDay()
         if self._clearOverdue:
             self.removeFailed(expiredOnly=True)
+        self.col.decks.recoverOrphans()
         decks = self.col.decks.all()
         decks.sort(key=itemgetter('name'))
         lims = {}