8e67a60053
is stored in _res_ext.sort_list, and sortlist for IPv4 is stored in _res.sort_list for backward compatibility. However, both sort_list's are maintaind by just one index _res.nsort. So, when IPv6 address is specified to sortlist, empty entry was created in _res.sort_list. It broke sortlist facility of gethostbyname(). Discussed on users@jp.ipv6.org.