Comparators don't interact correctly with trapped chests

Trapped chests don't power comparators 

Steps to reproduce:

1. Place down a trapped chest
2. Place redstone dust next to it
3. Add a comparator which would be activated by the dust
4. Open the trapped chest

Expected results:

The comparator activates

-

Observed results:

The comparator doesn't do anything

For more detail on this, see the attachments