avoid updating item if another annotation was added or edited since dispatching the update_item event

pandora/annotation/tasks.py

@@ -109,6 +109,7 @@ def update_item(id):
     from item.models import Item
     from clip.models import Clip
     a = models.Annotation.objects.get(pk=id)
+    if a.modified >= a.item.annotations.order_by('-modified')[0].modified:
         #cleanup orphaned clips
         Clip.objects.filter(item__id=a.item.id, annotations__id=None).delete()
         #update facets if needed