- For HTTPS if http2-prior-knowledge is set then only offer h2 (HTTP/2)
alpn to the server for protocol negotiation.
Prior to this change both HTTP/2 ("h2") and HTTP/1.1 ("http/1.1") were
offered for ALPN when http2-prior-knowledge was set.
CURL_HTTP_VERSION_2_PRIOR_KNOWLEDGE (tool: --http2-prior-knowledge) is
meant to send non-TLS HTTP requests HTTP/2 when it is known the server
supports them. However when HTTPS is used then it attempts to first
negotiate the connection with ALPN. In that case the user likely does
not want to offer http/1.1 to the server as an acceptable protocol.
Reported-by: kit-ty-kate@users.noreply.github.com
Fixes https://github.com/curl/curl/issues/9963
Closes https://github.com/curl/curl/pull/14266
b7e769dc87