func SetAgentRequested(ctx Context) {
	ctx.SetValue(contextKeyAgentRequest, true)
}
SetAgentRequested sets up the session context so that AgentRequested
returns true.
package ssh
import (
	"io"
	"io/ioutil"
	"net"
	"path"
	"sync"
	gossh "golang.org/x/crypto/ssh"
)
const (
	agentRequestType = "auth-agent-req@openssh.com"
	agentChannelType = "auth-agent@openssh.com"
	agentTempDir    = "auth-agent"
	agentListenFile = "listener.sock"
)
var contextKeyAgentRequest = &contextKey{"auth-agent-req"}