Always slim private & pass objects after delivery.

Fixes:	#1821

bin/varnishd/cache/cache_req_fsm.c

@@ -209,19 +209,20 @@ cnt_deliver(struct worker *wrk, struct req *req)
 
 	cnt_vdp(req, bo);
 
-	if (bo != NULL)
-		VBO_DerefBusyObj(wrk, &bo);
-
 	VSLb_ts_req(req, "Resp", W_TIM_real(wrk));
 
 	if (http_HdrIs(req->resp, H_Connection, "close"))
 		req->doclose = SC_RESP_CLOSE;
 
-	if ((req->objcore->flags & OC_F_PASS) && bo != NULL) {
-		VBO_waitstate(bo, BOS_FINISHED);
+	if (req->objcore->flags & (OC_F_PRIVATE | OC_F_PASS)) {
+		if (bo != NULL)
+			VBO_waitstate(bo, BOS_FINISHED);
 		ObjSlim(wrk, req->objcore);
 	}
 
+	if (bo != NULL)
+		VBO_DerefBusyObj(wrk, &bo);
+
 	(void)HSH_DerefObjCore(wrk, &req->objcore);
 	http_Teardown(req->resp);
 	return (REQ_FSM_DONE);

bin/varnishtest/tests/r01821.vtc

+varnishtest	"Slim down hit-for-pass objects"
+
+server s1 -repeat 2 {
+	rxreq
+	txresp -hdr "Cache-Control: max-age=5" -bodylen 65535
+} -start
+
+varnish v1 -vcl+backend {
+	sub vcl_backend_response {
+		set beresp.uncacheable = true;
+	}
+} -start
+
+logexpect l1 -v v1 {
+	expect * * Storage Transient
+} -start
+
+client c1 {
+	txreq -url /foo
+	rxresp
+	txreq -url /bar
+	rxresp
+} -run
+
+logexpect l1 -wait
+
+varnish v1 -expect SMA.Transient.c_bytes != 0
+varnish v1 -expect SMA.Transient.g_bytes < 65536