Merge branch 'fix_delete_set' into 'dev'

Fix delete_set form

See merge request federez/re2o!462

re2o/acl.py

@@ -255,7 +255,7 @@ def can_delete_set(model):
             all_objects = model.objects.all()
             instances_id = []
             for instance in all_objects:
-                can, _msg = instance.can_delete(request.user)
+                can, _msg, _reason = instance.can_delete(request.user)
                 if can:
                     instances_id.append(instance.id)
             instances = model.objects.filter(id__in=instances_id)