I would definitely pause.
I just took an internal course for interviewing potential candidates for our company a few weeks ago. Having been recently exposed to all the ways I can easily accidentally breach the law, I would agree that I would definitely hesitate, and may or may not answer the question.
Sure - in the comfort of my home office reading this thread, I have the luxury of being couch lawyer and arguing whether answering is legal or not, and how much I can divulge.
On the spot? I honestly might not have taken the risk if the question caught me off-guard (as it would've before today). As much as I want my manager to provide feedback often and early and for negative feedback to be constructive; and as much as I would want to exhibit those qualities myself; and as much as I think those things are important and should be discussed... I'd be uncomfortable sharing what is ultimately private information with, at that point, a random stranger.