IPv6 UDP server doesn't handle connections correctly

[sccarlson1]

I have two hosts running Ubuntu 12.04, with conntest 1.32. They are directly connected, and have addresses
server IPv4: 192.168.206.183
server IPv6: 3ffe::101/64
server IPv4: 192.168.206.182
server IPv6: 3ffe::100/64
On the server I ran
conntest -S discard -K 6000 -P UDP -l 10 -6
On the client I ran
conntest -P UDP -p 6000 -l 4 -6 -h 3ffe::101

Here is the tcpdump of this session:

18:15:21.780630 IP6 3ffe::100.50694 > 3ffe::101.6000: UDP, length 1024
18:15:22.781051 IP6 3ffe::100.50694 > 3ffe::101.6000: UDP, length 1024
18:15:23.781425 IP6 3ffe::100.50694 > 3ffe::101.6000: UDP, length 1024
18:15:24.781648 IP6 3ffe::100.50694 > 3ffe::101.6000: UDP, length 1024

But this is what the server reports:

Starting UDP discard server on *:6000

[890c1f8] Accepting UDP connection from 3ffe:::50694
[ ID] Interval Rx Rx/s Rx Pkts Rx Pkt/s
[890c1f8] 1.0- 1.0s 1.00 KiB 8.00 Kib/s 1 p 1 p/s
[890a810] Accepting UDP connection from 3ffe::100:50694
[ ID] Interval Rx Rx/s Rx Pkts Rx Pkt/s
[890a810] 1.0- 1.0s 2.00 KiB 16.00 Kib/s 2 p 2 p/s
[890a810] 2.0- 2.0s 1.00 KiB 8.00 Kib/s 1 p 1 p/s
[890c1f8] 0.0- 1.0s 1.00 KiB 8.00 Kib/s 1 p 1 p/s
[890c1f8] Expire UDP connection from 3ffe:::50694
[890a810] 0.0- 2.0s 3.00 KiB 12.00 Kib/s 3 p 1 p/s
[890a810] Expire UDP connection from 3ffe::100:50694

Compare this to the same commands, but using IPv4:
conntest -P UDP -p 6000 -l 4 -h 192.168.206.183
conntest -S discard -K 6000 -P UDP -l 10

Starting UDP discard server on *:6000

[9a2a1f8] Accepting UDP connection from 192.168.206.182:51888
[ ID] Interval Rx Rx/s Rx Pkts Rx Pkt/s
[9a2a1f8] 1.0- 1.0s 1.00 KiB 8.00 Kib/s 1 p 1 p/s
[9a2a1f8] 2.0- 2.0s 2.00 KiB 16.00 Kib/s 2 p 2 p/s
[9a2a1f8] 3.0- 3.0s 1.00 KiB 8.00 Kib/s 1 p 1 p/s
[9a2a1f8] 0.0- 3.0s 4.00 KiB 10.67 Kib/s 4 p 1 p/s
[9a2a1f8] Expire UDP connection from 192.168.206.182:51888