Skip EHOSTUNREACH by host issues

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@64774 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/rinda/test_rinda.rb

@@ -601,6 +601,8 @@ module RingIPv6
       return # IPv6 address for multicast not available
     rescue Errno::ENETDOWN
       return # Network is down
+    rescue Errno::EHOSTUNREACH
+      return # Unreachable for some reason
     end
     begin
       yield v6mc