Pinging IPv4 and v6 addresses can result in some hosts not being processed

Mixing IPv4 and v6 for pinging is creating problems and these problems are also different depending on your version of fping.

I have created 4 different example files with different address types and order and went across them with fping and fping6:

for f in pure-ipv4 pure-ipv6 mixed-ipv4-first mixed-ipv6-first; do
for fp in fping fping6; do
echo "${fp}" "${f}";
"${fp}" -f "${f}";
echo $?;echo "";
done;
done

The most noteworthy discovery is that the fping and fping6 commands in version 2 simply bail out of the file as soon as they encounter an address from a family they don't understand. Consequent hosts are not pinged at all; there are no results. Version 3 binaries on the other hand throw errors on unknown family's addresses but continue to go through the file.