user-v2: ping shows replies even for non-reachable addresses

[AkihiroSuda]

$ ping 1.2.3.4
PING 1.2.3.4 (1.2.3.4): 56 data bytes
Request timeout for icmp_seq 0
Request timeout for icmp_seq 1
^C
--- 1.2.3.4 ping statistics ---
3 packets transmitted, 0 packets received, 100.0% packet loss
$ limactl start --network=lima:user-v2
$ lima ping 1.2.3.4
PING 1.2.3.4 (1.2.3.4) 56(84) bytes of data.
64 bytes from 1.2.3.4: icmp_seq=1 ttl=64 time=0.968 ms
64 bytes from 1.2.3.4: icmp_seq=2 ttl=64 time=1.21 ms
^C
--- 1.2.3.4 ping statistics ---
2 packets transmitted, 2 received, 0% packet loss, time 1002ms
rtt min/avg/max/mdev = 0.968/1.090/1.213/0.122 ms

The situation is same for vz too.

[mhio]

I've seen this occur intermittently on vz as well but I haven't been able to replicate it.

From memory it was either early in boot or maybe before VM's are attached to the socket_vmnet process but I'll come back with something more concrete.