Try fix block

[vkill]

[benesch]

I'm reliably seeing this error message when I try to run the integration tests on this branch:

__run__session__userauth_password rets:[Ok(()), Ok(()), Ok(()), Ok(()), Ok(()), Ok(()), Ok(()), Err(Ssh2(Error { code: Session(-13), msg: "Failed getting banner" })), Ok(()), Ok(())]
thread 'integration_tests::session__userauth_password::simple_with_async_io' panicked at 'assertion failed: rets.iter().all(|x| x.is_ok())', async-ssh2-lite/tests/integration_tests/session__userauth_password.rs:73:9
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
test integration_tests::session__userauth_password::simple_with_async_io ... FAILED

Not sure if that's the same issue as #17, or something else.