Same prefix in Framed-IPv6-Address and Delegated-IPv6-Prefix results in no lease

With 2001:db8:0:0:5:: configured for both attributes in radius authorize file:

00:03:00:01:08:ff:ee:dd:cc:05    Cleartext-password := "08:ff:ee:dd:cc:05"
        Framed-IP-Address = "192.192.0.5",
        Framed-IPv6-Address = "2001:db8:0:0:5::",
        Delegated-IPv6-Prefix = "2001:db8:0:0:5::/96"

On processing a solicit, Kea logs this message, which, leaving aside the non-human-friendly id, seems like it is only logged in case of a programming error, since RadiusBackendImpl::get6() only does sanity checks, and doesn't fetch any hosts, and increments this counter of unexpected calls xcount6_ and always returns ConstHostPtr():

DEBUG RADIUS_BACKEND_GET6 spurious lookup for IPv6 subnet 2001 and id 0^@:0^C:0^@:0^A:0^H:0�:0�:0�:0�:0^E of type duid

Instead of logging this message which happens when the prefix for Framed-IPv6-Address is different than the prefix for Delegated-IPv6-Prefix:

DEBUG HOST_CACHE_GET_ONE_SUBNET_ID_IDENTIFIER_HOST using subnet id 2001 and identifier duid=0003000108FFEEDDCC04, found host: duid=0003000108FFEEDDCC04 ipv6_subnet_id=2001 hostname=(empty) ipv4_reservation=(no) siaddr=(no) sname=(empty) file=(empty) key=(empty) ipv6_reservation0=2001:db8::4:4:0:0 ipv6_reservation1=2001:db8:0:0:4::/96

The result is 2 x NoAvail:

DEBUG DHCP6_RESPONSE_DATA duid=[00:03:00:01:08:ff:ee:dd:cc:05], [no hwaddr info], tid=0x332f6a: responding with packet ADVERTISE (type 2), packet details: local_address=[ff02::1:2]:547, r>
msg_type=ADVERTISE (2), trans_id=0x332f6a,
options:
  type=00001, len=00010: 00:03:00:01:08:ff:ee:dd:cc:05
  type=00002, len=00014: 00:01:00:01:2d:e0:80:58:08:bf:b8:41:cf:ac
  type=00003(IA_NA), len=00055: iaid=64465, t1=0, t2=0,
options:
    type=00013, len=00039: NoAddrsAvail(2) "Sorry, no address could be allocated."
  type=00025(IA_PD), len=00056: iaid=94755, t1=0, t2=0,
options:
    type=00013, len=00040: NoPrefixAvail(6) "Sorry, no prefixes could be allocated."
No relays traversed.

Instead of what you would normally get which is 2 leases:

DEBUG DHCP6_RESPONSE_DATA duid=[00:03:00:01:08:ff:ee:dd:cc:04], [no hwaddr info], tid=0x332f6a: responding with packet ADVERTISE (type 2), packet details:>
msg_type=ADVERTISE (2), trans_id=0x332f6a,
options:
  type=00001, len=00010: 00:03:00:01:08:ff:ee:dd:cc:04
  type=00002, len=00014: 00:01:00:01:2d:e0:80:58:08:bf:b8:41:cf:ac
  type=00003(IA_NA), len=00040: iaid=64465, t1=1000, t2=2000,
options:
    type=00005(IAADDR), len=00024: address=2001:db8::4:4:0:0, preferred-lft=3000, valid-lft=4000
  type=00025(IA_PD), len=00041: iaid=94755, t1=1000, t2=2000,
options:
    type=00026(IAPREFIX), len=00025: prefix=2001:db8:0:0:4::/96, preferred-lft=3000, valid-lft=4000
No relays traversed.

https://gitlab.isc.org/isc-projects/forge/-/merge_requests/469

• test_RADIUS_Delegated_IPv6_Prefix_same_prefix
• test_RADIUS_Delegated_IPv6_Prefix_same_prefix_and_prefix_length