Don't consider pass an error when doing streaming fetch.

Patch by: tnt

bin/varnishd/cache_center.c

@@ -930,13 +930,13 @@ cnt_streambody(struct sess *sp)
 	AZ(sp->vbc);
 	AN(sp->director);
 
-	if (!i && sp->obj->objcore != NULL) {
+	if (i)
+		sp->doclose = "Stream error";
+	else if (sp->obj->objcore != NULL) {
 		EXP_Insert(sp->obj);
 		AN(sp->obj->objcore);
 		AN(sp->obj->objcore->ban);
 		HSH_Unbusy(sp);
-	} else {
-		sp->doclose = "Stream error";
 	}
 	sp->wrk->acct_tmp.fetch++;
 	sp->director = NULL;

bin/varnishtest/tests/r01157.vtc

+varnishtest "#1157 - Connection close on pass and do_stream"
+
+server s1 {
+	rxreq
+	txresp
+	expect req.url == "/"
+
+	rxreq
+	txresp
+	expect req.url == "/"
+} -start
+
+varnish v1 -vcl+backend {
+	sub vcl_recv { return (pass); }
+	sub vcl_fetch {	set beresp.do_stream = true; }
+} -start
+
+client c1 {
+	txreq -url /
+	rxresp
+	expect resp.status == 200
+
+	txreq -url /
+	rxresp
+	expect resp.status == 200
+} -run