Use vendoring for backward compatibility The switch of the Madon library to Go modules breaks builds with Go version < 1.11 since the import path now contains "v2". This patch adds vendoring so that it can still build with those versions. Let's try to re-enable Travis builds with Go v1.8-1.11...

// +build !go1.8

package websocket

import (
	"crypto/tls"
	"net/http/httptrace"
)

func doHandshakeWithTrace(trace *httptrace.ClientTrace, tlsConn *tls.Conn, cfg *tls.Config) error {
	return doHandshake(tlsConn, cfg)
}