// and then proxies to w.
// It proxies Read calls to a reader it receives from rch.
type logWritesConn struct {
	net.Conn // nil. crash on use.

	w io.Writer

	rch <-chan io.Reader
	r   io.Reader // nil until received by rch

	mu     sync.Mutex
	writes []string
}

func (c *logWritesConn) Write(p []byte) (n int, err error) {
	c.mu.Lock()