Don't send both c-l and chunked to backend for h2.

Fixes #2247

bin/varnishd/http2/cache_http2_proto.c

@@ -473,6 +473,7 @@ h2_do_req(struct worker *wrk, void *priv)
 {
 	struct req *req;
 	struct h2_req *r2;
+	const char *b;
 
 	CAST_OBJ_NOTNULL(req, priv, REQ_MAGIC);
 	CAST_OBJ_NOTNULL(r2, req->transport_priv, H2_REQ_MAGIC);
@@ -483,6 +484,15 @@ h2_do_req(struct worker *wrk, void *priv)
 	// XXX: Have I mentioned H/2 Is hodge-podge ?
 	http_CollectHdrSep(req->http, H_Cookie, "; ");	// rfc7540,l,3114,3120
 
+	if (req->req_body_status == REQ_BODY_INIT) {
+		if (!http_GetHdr(req->http, H_Content_Length, &b))
+			req->req_body_status = REQ_BODY_WITHOUT_LEN;
+		else
+			req->req_body_status = REQ_BODY_WITH_LEN;
+	} else {
+		assert (req->req_body_status == REQ_BODY_NONE);
+	}
+
 	req->http->conds = 1;
 	if (CNT_Request(wrk, req) != REQ_FSM_DISEMBARK) {
 		AZ(req->ws->r);
@@ -517,8 +527,6 @@ h2_end_headers(struct worker *wrk, const struct h2_sess *h2,
 
 	if (h2->rxf_flags & H2FF_HEADERS_END_STREAM)
 		req->req_body_status = REQ_BODY_NONE;
-	else
-		req->req_body_status = REQ_BODY_WITHOUT_LEN;
 
 	req->req_step = R_STP_TRANSPORT;
 	req->task.func = h2_do_req;

bin/varnishtest/tests/t02005.vtc

@@ -4,6 +4,8 @@ barrier b1 cond 2
 
 server s1 {
 	rxreq
+	expect req.http.content-length == 7
+	expect req.http.transfer-encoding == <undef>
 	barrier b1 sync
 	txresp -hdr "Content-Type: text/plain" -body response
 } -start

bin/varnishtest/tests/t02006.vtc

@@ -4,6 +4,8 @@ barrier b1 cond 2
 
 server s1 {
 	rxreq
+	expect req.http.content-length == <undef>
+	expect req.http.transfer-encoding == chunked
 	expect req.proto == HTTP/1.1
 	barrier b1 sync
 	txresp -hdr "Content-Type: text/plain" -body response
@@ -21,7 +23,6 @@ client c1 {
 			-nohdrend
 		txcont \
 			-hdr expect 100-continue \
-			-hdr content-length 7 \
 			-nostrend
 
 		rxhdrs