IPv6 URL support in SVN? v1.8.4 works with IPv4, not with IPv6

[darx]

With my resolvers set to IPv6

        cat /etc/resolv.conf
                nameserver 2600:3c01::2 
                nameserver 2600:3c01::3
                options rotate

lookups work

        dig A    www.nlnetlabs.nl      +short
                213.154.224.1
        dig A    git.varnish-cache.org +short
                194.31.39.164
        dig AAAA www.nlnetlabs.nl      +short
                2001:7b8:206:1::1
        dig AAAA git.varnish-cache.org +short
                (empty)

git, e.g., works

        git clone git://git.varnish-cache.org/varnish-cache varnish-test
                Cloning into 'varnish-test'...
                remote: Counting objects: 67047, done.
                remote: Compressing objects: 100% (19821/19821), done.
                remote: Total 67047 (delta 51735), reused 61991 (delta
                47133)
                Receiving objects: 100% (67047/67047), 10.23 MiB | 154
                KiB/s, done.
                Resolving deltas: 100% (51735/51735), done.

in short, 'everything' IPv6 works here ... except for subversion,

        svn co http://www.nlnetlabs.nl/svn/nsd/tags/NSD_4_0_0_REL/
        nsd4-test
                svn: E175002: Unable to connect to a repository at URL
                'http://www.nlnetlabs.nl/svn/nsd/tags/NSD_4_0_0_REL'
                svn: E175002: OPTIONS of
                'http://www.nlnetlabs.nl/svn/nsd/tags/NSD_4_0_0_REL':
                Could not resolve hostname `www.nlnetlabs.nl': Host not
                found (http://www.nlnetlabs.nl)

reading @

        @
        
http://www.wandisco.com/svnforum/threads/54273-svn-error-when-checkout-from-ipv6-url

IPv6 support is (?) in svn v>1.8

checking locally

        svn --version
                svn, version 1.7.13 (r1516569)

so, upgrading to

        svn --version
                svn, version 1.8.4 (r1534716)

retrying with new version still fails,

        svn co http://www.nlnetlabs.nl/svn/nsd/tags/NSD_4_0_0_REL/
        nsd4-test
                svn: E670002: Unable to connect to a repository at URL
                'http://www.nlnetlabs.nl/svn/nsd/tags/NSD_4_0_0_REL'
                svn: E670002: Name or service not known

changing resolvers to IPv4

        cat /etc/resolv.conf
                nameserver 74.207.241.5 
                nameserver 74.207.242.5 
                options rotate

now, retrying works

        svn co http://www.nlnetlabs.nl/svn/nsd/tags/NSD_4_0_0_REL/
        nsd4-test
                ...
                Checked out revision 4089.

clearly, IPv4 usage in svn works; IPv6 doesn't.  At least -- here.

reading CHANGES, and poking around in upstream sources, it's not clear
to me what that status of IPv6 support in SVN is.

IS there full IPv6 support in svn?

darx