So we don't have to depend on network stack probing to decide whether ipv4 or ipv6 will be used. While at it, also prevent a race report when doing the same parallel resolving for os resolver, even though this race is harmless.
Connecting to API using ipv6 sometimes hang at TLS handshake, using ipv4 only so we can fetch the config more reliably. Fixed #53
Cuong Manh Le