[ruby/ipaddr] Remove warning by asserting its presence
$ rake test >/dev/null /tmp/test/test_ipaddr.rb:202: warning: IPAddr#ipv4_compat is obsolete
https://github.com/ruby/ipaddr/commit/31d62407c2
[ruby/ipaddr] Remove warning by asserting its presence
https://github.com/ruby/ipaddr/commit/31d62407c2