Fix copy of ItemValue when const qualifier is removed

src/mesh/ItemValue.hpp

@@ -40,7 +40,7 @@ class ItemValue
   friend PUGS_INLINE ItemValue<std::remove_const_t<DataType>, item_type, ConnectivityPtr>
   copy(const ItemValue<DataType, item_type, ConnectivityPtr>& source)
   {
-    ItemValue<std::remove_const_t<DataType>, item_type, ConnectivityPtr> image(source);
+    ItemValue<std::remove_const_t<DataType>, item_type, ConnectivityPtr> image(*source.connectivity_ptr());
 
     image.m_values = copy(source.m_values);
     return image;