error when download keysign via ipv6
error when download keysign via ipv6

When you try to `make release` keys.gnupg.net may be resolved to an IPv6 address. Under some circumstances (e.g. an internet connection that does not support IPv6) the build sistematically fail with message:
"gpg: keyserver receive failed: Cannot assign requested address"
I created a fallback to an IPv4 version of keyserver.
rancher/os-kernel