tls: debug line cleanup

Remove annoying information in debug log.

Change-Id: I0f935b2753b9a0e9b168571e1a5ff0e119ffa474
Tuleap: #660

src/security/tls_session.cpp

@@ -640,6 +640,7 @@ TlsSession::handleStateHandshake(TlsSessionState state)
     // Continue handshaking on non-fatal error
     if (ret != GNUTLS_E_SUCCESS) {
         // TODO: handle GNUTLS_E_LARGE_PACKET (MTU must be lowered)
+        if (ret != GNUTLS_E_AGAIN)
             RING_DBG("[TLS] non-fatal handshake error: %s", gnutls_strerror(ret));
         return state;
     }