Turning TCP_CLIENT_REFRESH into TCP_REFRESH_HIT

I've noticed that Netscape Communicator seems to put "pragma no-cache" into
just about every fetch, causing major performance problems against popular
sites as it keeps flushing the objects everyone else could have had returned
as cache hits. I'd like to make Squid do an IMS GET for a no-cache request in
the case where it already has the object (i.e. treat it as a request for a
stale object) instead of purging it and fetching from source[1].

Can anyone point me to the right bits of code to look at?

Thanks,

[1] Actually, I'd like Netscape to fix their browser, but....

-- 
Tim Smith
(tim@zynet.net)