knot-dns download fails with ipv6
$ wget -c https://secure.nic.cz/files/knot-dns/knot-2.7.1.tar.xz.asc --2018-08-21 22:06:44-- https://secure.nic.cz/files/knot-dns/knot-2.7.1.tar.xz.asc Resolving secure.nic.cz (secure.nic.cz)... 2001:1488:800:400::2:102, 217.31.204.102 Connecting to secure.nic.cz (secure.nic.cz)|2001:1488:800:400::2:102|:443... failed: Connection refused. Connecting to secure.nic.cz (secure.nic.cz)|217.31.204.102|:443... connected. HTTP request sent, awaiting response... 200 OK Length: 801 [text/plain] Saving to: ‘knot-2.7.1.tar.xz.asc’
100%[======================================>] 801 --.-K/s in 0s
2018-08-21 22:06:44 (61.0 MB/s) - ‘knot-2.7.1.tar.xz.asc’ saved [801/801]
