pkg/30521: svn connection to IPv6/IPv4 servers from IPv4-only host fails with No route to host

[rdenis%simphalempin.com@localhost]

>Number:         30521
>Category:       pkg
>Synopsis:       svn connection to IPv6/IPv4 servers from IPv4-only host fails 
>with No route to host
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Jun 14 09:00:00 +0000 2005
>Originator:     Rémi Denis-Courmont
>Release:        2.0
>Organization:
>Environment:
NetBSD raymonde.via.ecp.fr 2.0 NetBSD 2.0 (GENERIC) #0; Wed Dec  1 10:58:25 UTC 
2004  builds@build:/big/builds/ad/netbsd-2-0-RELEASE/i386/200411300000Z-obj/big/
builds/ab/netbsd-2-0-RELEASE/src/sys/arch/i386/compile/GENERIC i386
>Description:
My system only has IPv4 connectivity (i.e. no default IPv6 route/gateway).

When I try to connect to a svnserve on a dual-stack IPv6/IPv4 server, svn fails 
with "No route to host". The only work-around is to specify a DNS name for the 
server that does only resolve to IPv4, or to put the raw server's IPv4, so that 
svn doesn't attempt to connect with IPv6.

svn should fallback to IPv4 when IPv6 connection fails, like normal 
applications do when they use getaddrinfo().
>How-To-Repeat:
- Build or install subversion-base package.
- Make sure IPv6 connectivity is *NOT* available on the host.
- Run:
  # svn ls svn://svn.simphalempin.com/miredo/trunk
  It will fail.

- If you run:
  # svn ls svn://138.195.157.222/miredo/trunk
  it will work (provided the server is not down).
>Fix: