icp bitrot?

icp v2 and v3 seem more different than I expected....

specifically, on the reply, the v3 code doesn't deal with reachability,
but v2 does. This doesn't affect the return data, only the opcode. The
opcode sent on unreachable sites is one used by v3 as well, so the
protocol doesn't seem to specify this behaviour.

Any suggestions?

Rob