[FS#681] Prefix Delegation is Broken (both ULA-Prefix and DHCPv6-PD Prefix)

[LEDE Bugs]

A new Flyspray task has been opened.  Details are below. 

User who did this - Christopher Friedt (cfriedt) 

Attached to Project - LEDE Project
Summary - Prefix Delegation is Broken (both ULA-Prefix and DHCPv6-PD Prefix)
Task Type - Bug Report
Category - Base system
Status - Unconfirmed
Assigned To - 
Operating System - All
Severity - Low
Priority - Very Low
Reported Version - Trunk
Due in Version - Undecided
Due Date - Undecided
Details - Supply the following if possible:
 - Device problem occurs on

TP-Link TL-WDR3600 v1

 - Software versions of LEDE release, packages, etc.

LEDE Reboot 17.01.0 r3205-59508e3 / LuCI lede-17.01 branch (git-17.051.53299-a100738)

 - Steps to reproduce
   
1) From a fresh install, under Network -> Interfaces, change wan6 to pppoe-wan6.
2) Add ADSL credentials
3) Apply & Save
4) Go to Status -> Overview, and note the Prefix Delegated: AAAA:BBBB:CCCC:DDDD::/56
5) Go to Network -> Interfaces -> Global Network Options, and note the IPv6 ULA-Prefix: EEEE:FFFF:GGGG::/48
3) Under Network -> DHCP and DNS -> Static Leases, add a new lease
foo / [mac addr] / 192.168.1.12 /  / c
4) Apply & Save
5) go to machine "foo", and check IP addresses
5.a) $ ifconfig en0 | grep "inet "
	inet 192.168.1.12 netmask 0xffffff00 broadcast 192.168.1.255
5.b) $ ifconfig en0 | grep "inet6 AAAA:BBBB:CCCC:DDDD.* secured\|inet6 EEEE:FFFF:GGGG.* secured"
	inet6 AAAA:BBBB:CCCC:DDDD:1cd5:b444:dd36:37ab prefixlen 64 autoconf secured 
	inet6 EEEE:FFFF:GGGG::cf5:d587:2730:5d88 prefixlen 64 autoconf secured
6) From another machine on the network, not that ping6 foo resolves to address EEEE:FFFF:GGGG::c

Actual IPv6 address(es) assigned:
Global: AAAA:BBBB:CCCC:DDDD:1cd5:b444:dd36:37ab
ULA: EEEE:FFFF:GGGG::cf5:d587:2730:5d88

Expected IPv6 address(es) assigned:
Global: AAAA:BBBB:CCCC:DDDD::c
ULA: EEEE:FFFF:GGGG::c

I hope I don't have the completely wrong interpretation, but that one seemed the most intuitive. 

Just as a hint, I inspected /etc/init.d/dnsmasq::dhcp_host_add() and it does not query the ula_prefix at all (e.g. uci_get network @globals[0] ula_prefix) nor does it query the PD prefix at all.

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=681