can set owner for a slave

tiramisu/storage/dictionary/value.py

@@ -115,10 +115,12 @@ class Values(Cache):
         idx = self._values[0].index(path)
         if isinstance(self._values[3][idx], list):
             if index is None:
-                raise ValueError('list but no index')
-            owner = list(self._values[3][idx])[index] = owner
+                raise ValueError('Slave need index to set owner')
+            towner = list(self._values[3][idx])
+            towner[index] = owner
+            owner = towner
         elif index is not None:
-            raise ValueError('index set but not a list')
+            raise ValueError('Only slave option needs index to set owner')
         lst = list(self._values[3])
         lst[idx] = owner
         values = list(self._values)