Refactor new session ticket

Signed-off-by: Jerry Yu <jerry.h.yu@arm.com>
diff --git a/library/ssl_tls13_server.c b/library/ssl_tls13_server.c
index 607347d..f31e7ab 100644
--- a/library/ssl_tls13_server.c
+++ b/library/ssl_tls13_server.c
@@ -2832,6 +2832,8 @@
      * Note: We currently don't have any extensions.
      * Set length to zero.
      */
+    ssl->handshake->sent_extensions = MBEDTLS_SSL_EXT_MASK_NONE;
+
     MBEDTLS_SSL_CHK_BUF_PTR( p, end, 2 );
     MBEDTLS_PUT_UINT16_BE( 0, p, 0 );
     p += 2;