ldap in mozilla and IPv6

The bug has existed for so long:
ipv6 enabled on winxp
thunderbird, mozilla etc address book hangs because the ldap connection tries to create IPv6 socket to IPv4 address.

So easy to fix, why hasn't it happened?
I'd fix it for them, but haven't followed it through.
I note some statements about IPv6 support in latest mozilla stuff, but so far no fix.

The ldap directory service attempts to
connect to the ipv6 socket ::ffff:xx.xx.xx.xx instead of the ipv4 socket
xx.xx.xx.xx

This is consistent with the last few years and on the thunderbird 3.0a1 that I
just downloaded/installed it still fails in the same way on a dual hosted ipv4
ipv6 machine.
Logging ldap:5 only produces the following:
0[274310]: nsLDAPOperation::SimpleBind(): called; bindName = '';
2348[278d2d0]: nsLDAPConnection::Run() entered