According to https://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-05 it is "http/1.1" and not "http/1.0".
Add ALPN support when using GnuTLS >= 3.2.0. This allows libcurl to negotiate HTTP/2.0 for https connections when built with GnuTLS. See: http://www.gnutls.org/manual/gnutls.html#Application-Layer-Protocol-Negotiation-_0028ALPN_0029 http://tools.ietf.org/html/draft-ietf-tls-applayerprotoneg-04