get_host_addresses crashes with 'called `Option::unwrap()` on a `None` value'

[pmer]

The net::get_host_addresses fails on some addresses. It failed on 0.8 and it still fails on master, at least with b3ff24a from November 24th.

STEPS TO REPRODUCE

$ cat break.rs
use std::io::net::get_host_addresses;

fn main() {
        get_host_addresses("irc.n0v4.com");
}
$ rustc break.rs
$ ./break
task '<main>' failed at 'called `Option::unwrap()` on a `None` value', /home/USER/rust-master/src/libstd/option.rs:135

The above code is for reproducing on master. For 0.8, change the import from std::io::net::get_host_addresses to std::rt::io::net::get_host_addresses.