User permission override not detected

In a fresh install of the Commons distribution, I've removed the "post comments" and "post comments without approval" permissions from the authenticated user role. I would expect these changes to show up as overrides to the Commons core feature in the "Item" dropdown at admin/build/features/features-override/add, but these overrides are not listed.

Initial troubleshooting shows that Features does recognize that component as overridden, but this is not properly detected somewhere in features_override_detect_overrides().

I've done a drush cc all for good measure.