dhcp6-pd sla-len and error dd_ifprefix: invalid prefix length 63 + 4 + 64 = wide dhcp6 bug

I am trying to get the below config to work with Comcast business cable.

The config for one is generating incorrect request for DNS as you can see I have asked for none. Two the error I know is caused be the sla-len not being set to 1, I have a working config that uses the same setting but changing sla-len to 1 and all interfaces get an IP.

We are requesting a /60 as is what the modem is configured to give and that is what we want to be able to configure more than one interface with it's own network.

description WAN
 dhcpv6-pd {
     no-dns
     pd 0 {
         interface eth0.5 {
             host-address ::1
             prefix-id :2
             service slaac
         }
         interface eth0.10 {
             host-address ::1
             prefix-id :4
             service slaac
         }
         interface eth0.20 {
             host-address ::1
             prefix-id :3
             service slaac
         }
         interface vtun0 {
             host-address ::1
             prefix-id :1
         }
         prefix-length /60
     }
     rapid-commit enable
 }

# This file was auto-generated by /opt/vyatta/sbin/dhcpv6-pd-client.pl
# configuration sub-system.  Do not edit it.

interface eth0.30 {
        send ia-na 0;
        request domain-name-servers, domain-name;
        send rapid-commit;
        send ia-pd 0;
        script "/opt/vyatta/sbin/ubnt-dhcp6c-script";
};

id-assoc na 0 {};

id-assoc pd 0 {
        prefix ::/60 infinity;
        prefix-interface eth0.5 {
                sla-id 2;
                sla-len 4;
                ifid 1;
        };
        prefix-interface eth0.10 {
                sla-id 4;
                sla-len 4;
                ifid 1;
        };
        prefix-interface eth0.20 {
                sla-id 3;
                sla-len 4;
                ifid 1;
        };
        prefix-interface vtun0 {
                sla-id 1;
                sla-len 4;
                ifid 1;
        };
};

With the above generated wide dhcp6 config this is the error I get when running in debug

May/16/2016 11:50:28: add_ifprefix: invalid prefix length 63 + 4 + 64
May/16/2016 11:50:28: add_ifprefix: invalid prefix length 63 + 4 + 64
May/16/2016 11:50:28: add_ifprefix: invalid prefix length 63 + 4 + 64
May/16/2016 11:50:28: add_ifprefix: invalid prefix length 63 + 4 + 64

I am not sure whre the 63 is coming from, I have deleted the DUID just before starrting the client, so there should be nothing that would make it even thing the prefix length is 63.

I also have run this on a linux machine with simular configuration at I can get each interface an address with the above config chaging the sla-len to 1.

Is it possible to configure this with an option for changing sla-len since the wide dhcp client seems to think that /60 is a 63. I know this is a wide dhcp bug, but the simple fix is just change sla-len for now until someone fixes the code.

Thanks