collapsed_forwarding and ICP

If I have a peer and it has collapsed_forwarding on, at what point
will it return an ICP_HIT to me? E.g.,

1) As soon as there's an outstanding (therefore collapsed) request for
it?
2) As soon as there's a cacheable response in-flight for it?
3) Only when the entire response is in-cache?

My reading of the code is that it's #1. Do I have this right?

If that's the case:
- On the plus side, this helps collapse requests across peers.
- On the down side, it seems like there's the potential for requests
to go to peers, only to find that the response is uncacheable.

Thanks,

--
Mark Nottingham       mnot_at_yahoo-inc.com