debian-add_ip.sh does not properly setup IPv6 route for Lenny containers

The /etc/vz/dists/scripts/debian-add_ip.sh script found in the 3.0.23-1dso1 vzctl Debian-Systs package does not properly setup the IPv6 default route for Debian Lenny containers. It works correctly for Debian Etch containers.

The reason seems to be that the default behavior of the ifconfig command changed from etch to lenny: when adding IPv6 addresses without specifying a prefixlen, the prefixlen is assumed to be /128 in Lenny instead of /0 in etch.

The attached patch restores the Etch behavior for both Etch and Lenny containers by explicitly specifying the prefix length in ifconfig commands.

But it seems curious that the setup of the default route depends on the /0 netmask. For example, RedHat/Centos containers have a working default IPv6 route but a /128 netmask.

Manually adding the default route inside a Lenny container started with unmodified (buggy) debian-add_ip.sh and /128 netmask, using the /sbin/ip command (from iproute package), works as expected. However the iproute package is not included in the standard Debian templates, and is not a mandatory package in a stand-alone Debian installation; so debian-add_ip.sh should not rely on it.