remote-curl: store the protocol version the server responded with

Store the protocol version the server responded with when performing
discovery.  This will be used in a future patch to either change the
'Git-Protocol' header sent in subsequent requests or to determine if a
client needs to fallback to using a different protocol version.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

remote-curl.c

@@ -171,6 +171,7 @@ struct discovery {
 	size_t len;
 	struct ref *refs;
 	struct oid_array shallow;
+	enum protocol_version version;
 	unsigned proto_git : 1;
 };
 static struct discovery *last_discovery;
@@ -184,7 +185,8 @@ static struct ref *parse_git_refs(struct discovery *heads, int for_push)
 			   PACKET_READ_CHOMP_NEWLINE |
 			   PACKET_READ_GENTLE_ON_EOF);
 
-	switch (discover_version(&reader)) {
+	heads->version = discover_version(&reader);
+	switch (heads->version) {
 	case protocol_v2:
 		die("support for protocol v2 not implemented yet");
 		break;