[4.1] 1a92e35 Add a missing VDP flush operation after ESI:includes.

[Lasse Karstensen]

commit 1a92e35518210636e09cfb485a692de7570a218b
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Tue Feb 2 00:22:04 2016 +0000

    Add a missing VDP flush operation after ESI:includes.
    
    In incredibly seldom circumstances this bug would cause ESI:include
    data to be bad.
    
    Fixes:	#1852

diff --git a/bin/varnishd/cache/cache_esi_deliver.c b/bin/varnishd/cache/cache_esi_deliver.c
index abc705b..1bfd365 100644
--- a/bin/varnishd/cache/cache_esi_deliver.c
+++ b/bin/varnishd/cache/cache_esi_deliver.c
@@ -761,6 +761,7 @@ VED_Deliver(struct req *req, struct busyobj *bo, int wantbody)
 		else
 			VDP_push(req, ved_vdp_bytes, ecx->preq, 1);
 		(void)VDP_DeliverObj(req);
+		(void)VDP_bytes(req, VDP_FLUSH, NULL, 0);
 	}
 	VDP_close(req);
 }