If you hold the home button for Siri and pull down NC at the same time, Siri gets cut off.
How is this a bug? I would think its working as designed. BTW just for kicks I tried it and you cannot pull down NC while Siri is on. Both locked and unlocked. Looks like folks are really grasping to find something to B**** about. Or falsely posting bugs on the wiki just for grins.
However this did cause me to discover something. Not sure if new or been around forever but while Siri is listening and pops up any text, such as "go ahead I am listening" you can drag that text down and see past requests!