Test sys::test_socket::test_vsock fails on Ubuntu 20.10/AMD64 beta

[tommythorn]

Tested nix@566e2d7dad025c9b2bef98115b584328c145675d using rust 1.47.0 (stable) on Ubuntu 20.04/AMD64 (up to date at time of testing)

cargo test hangs on test_af_alg_aead (to be file after this one). Once commented out, it fails with

failures:

---- sys::test_socket::test_vsock stdout ----
thread 'sys::test_socket::test_vsock' panicked at 'assertion failed: `(left == right)`
  left: `None`,
 right: `Some(Sys(EADDRNOTAVAIL))`', test/sys/test_socket.rs:1440:5