Warning: Invalid ipv6 header in skb

**Describe the issue**
From time to time Tempesta prints into dmesg warning
```
Warning: Invalid ipv6 header in skb
```
Need to investigate a reason of it.

**To Reproduce**
Start Tempesta and wait. I believe need to have configured ipv6 interface.

**Version or commit hash**
dda57969495c20930bddc587ca3559548eca0a18