CORD-1632: Eliminate dead reference to slice.site

Change-Id: I21b6493ccbeba7f63a6adfcb4ac5f6a98b10f3b9
(cherry picked from commit db071c1d6db93b4d8644ac9cf211c8c2ed1498b2)
diff --git a/xos/core/models/attic/slice_model.py b/xos/core/models/attic/slice_model.py
index ca4e005..c057f2a 100644
--- a/xos/core/models/attic/slice_model.py
+++ b/xos/core/models/attic/slice_model.py
@@ -21,7 +21,6 @@
     return "%s_%s" % (self.site.login_base, self.name)
 
 def __xos_save_base(self, *args, **kwds):
-    site = Site.objects.get(id=self.site.id)
     # set creator on first save
     if not self.creator and hasattr(self, 'caller'):
         self.creator = self.caller