Comment 4 for bug 1372883

Reviewed: https://review.openstack.org/147799
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=82bf4afdf9a80a3f7875d1908c5fac17fd037fee
Submitter: Jenkins
Branch: stable/juno

commit 82bf4afdf9a80a3f7875d1908c5fac17fd037fee
Author: Alexey I. Froloff <email address hidden>
Date: Tue Sep 30 16:37:19 2014 +0400

    Specify prefix length for IPv6 subnets

    If Network contains dhcpv6-stateful Subnet with prefix other than /64,
    dnsmasq refuses to start if prefix-len is not specified in dhcp-range
    option. From dnsmasq(8) manpage:

        For IPv6, the parameters are slightly different: instead of netmask
        and broadcast address, there is an optional prefix length which must
        be equal to or larger then the prefix length on the local interface.
        If not given, this defaults to 64. Unlike the IPv4 case, the prefix
        length is not automatically derived from the interface
        configuration. The mimimum size of the prefix length is 64.

    It is safe to always specify prefix length, so dnsmasq will use correct
    configuration.

    Change-Id: Ibef1f55926585016f0054accd7f7ef5a022e3fe1
    Closes-Bug: #1372883
    (cherry picked from commit f996a7b46878f543ecf775380529af10fe87b8cb)