Current -cvs crashing when invalid hostname in client requested URL

[Reuben Farrelly]

Seems to be new breakage in the last few days, but if I try to surf to a URL 
which is invalid eg www.fireeeefox.org, squid-3/CVS dies an ugly death:

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 47741279648528 (LWP 29234)]
0x000000000043543c in clientReplyContext::processMiss (this=0x2b6ba27dd028)
    at ../include/RefCount.h:110
110                 p.p_->RefCountReference();
(gdb) bt full
#0  0x000000000043543c in clientReplyContext::processMiss (this=0x2b6ba27dd028)
    at ../include/RefCount.h:110
        url = Variable "url" is not available.
(gdb) frame 0
#0  0x000000000043543c in clientReplyContext::processMiss (this=0x2b6ba27dd028)
    at ../include/RefCount.h:110
110                 p.p_->RefCountReference();
(gdb) frame 1
#1  0x00000000004358e8 in clientReplyContext::doGetMoreData (
    this=0x2b6ba27dd028) at client_side_reply.cc:1718
1718            processMiss();
(gdb) frame 2
#2  0x00000000004389b6 in ClientHttpRequest::httpStart (this=0xbddeb8)
    at client_side_request.cc:953
953         clientStreamRead(node, this, node->readBuffer);
(gdb) frame 3
#3  0x000000000043970f in ClientHttpRequest::doCallouts (this=0xbddeb8)
    at client_side_request.cc:1097
1097        processRequest();
(gdb) frame 4
#4  0x000000000040c305 in ACLChecklist::checkCallback (this=0xbefa98,
    answer=ACCESS_ALLOWED) at ACLChecklist.cc:248
248             callback_(answer, cbdata_);
(gdb) frame 5
#5  0x000000000047ec90 in ipcacheCallback (i=0x83c620) at ipcache.cc:265
265             callback(i->flags.negcached ? NULL : &i->addrs, cbdata);
(gdb) frame 6
#6  0x00000000004520ae in idnsCallback (q=0x2b6ba2800010, answers=0x0, n=-3,
    error=0x51e158 "Name Error: The domain name does not exist.")
    at dns_internal.cc:877
877                 callback(cbdata, answers, n, error);
(gdb) frame 7
#7  0x000000000045384a in idnsGrokReply (buf=Variable "buf" is not available.
) at dns_internal.cc:984
984         idnsCallback(q, message->answer, n, q->error);
(gdb) frame 8
#8  0x0000000000453d9a in idnsRead (fd=8, data=Variable "data" is not available.
) at dns_internal.cc:1052
1052            idnsGrokReply(rbuf, len);
(gdb) frame 9
#9  0x0000000000444ad6 in comm_select (msec=Variable "msec" is not available.
) at comm_epoll.cc:269
269                     hdl(fd, F->read_data);
(gdb) frame 10
#10 0x00000000004813ba in main (argc=Variable "argc" is not available.
) at main.cc:1177
1177            switch (comm_select(loop_delay)) {
(gdb) info locals
wait = 4294967295
loop_delay = Variable "loop_delay" is not available.
(gdb)

100% reproduceable.

Reuben