The default version (TLS 1.2) is no longer overridden with TLS 1.3 so
the server must explicitly set it.

Fixes: ("crypto/tls: allow client to pick TLS 1.3, do not enable it by default.")

This makes it easier to validate the handshake contents using Wireshark.

Use Go 1.9 (go1.9) with a patch to enable users to access the 0RTT API:

    net/http: attach TLSConnContextKey to the request Context

HEAD is currently breaking the build.

ConfirmHandshake should block on a Read until the handshakeConfirmed
state is reached, but past that it shouldn't.

There is no reason a server can't just send a CloseNotify in its first
flight, and then close the connection without reading the 0-RTT data.

Also, it's not expected of Close to block on reading, and interlocking
with a Read can cause a deadlock.

Fixes NCC-2016-001