no longer need new request after opendir stat

PR #257 fixes the issue with running Stat and Readdir on the same
Request. Thus we no longer need to close and recreate the Request
when handling an Opendir call.
diff --git a/request-server.go b/request-server.go
index c533e7a..604b20d 100644
--- a/request-server.go
+++ b/request-server.go
@@ -175,10 +175,8 @@
 		case *sshFxpOpendirPacket:
 			request := requestFromPacket(ctx, pkt)
 			rpkt = request.call(rs.Handlers, pkt)
-			request.close()
 			if stat, ok := rpkt.(*sshFxpStatResponse); ok {
 				if stat.info.IsDir() {
-					request := requestFromPacket(ctx, pkt)
 					handle := rs.nextRequest(request)
 					rpkt = sshFxpHandlePacket{pkt.id(), handle}
 				} else {