Fix API guidielines typo

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>
Correctly intersect * and U

There was a case where * & U could be evaluated to U. This was due trying too
hard to combine the code paths for * and U. We've separated them by a mile now.

Signed-off-by: Casey Dahlin <cdahlin@redhat.com>