Fix creation of duplicate ControllerSlice objects when Controllers are modified
diff --git a/xos/model_policies/model_policy_Controller.py b/xos/model_policies/model_policy_Controller.py
index fa84be7..2db7a63 100644
--- a/xos/model_policies/model_policy_Controller.py
+++ b/xos/model_policies/model_policy_Controller.py
@@ -22,7 +22,7 @@
     slices = Slice.objects.all()
     for slice in slices:
         if slice not in ctrls_by_slice or \
-            controller not in ctrls_by_slice:
+            controller not in ctrls_by_slice[slice]:
             controller_slice = ControllerSlice(controller=controller, slice=slice)
             controller_slice.save()
     # relations for all users