[master] dba2321 Add an assert to show Coverity we know what we do.

[Poul-Henning Kamp]

commit dba232196619238be04bb43b2101d1af6eef4228
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Tue Oct 1 16:03:46 2013 +0000

    Add an assert to show Coverity we know what we do.

diff --git a/bin/varnishd/cache/cache_backend_poll.c b/bin/varnishd/cache/cache_backend_poll.c
index 4cc03ce..53d1183 100644
--- a/bin/varnishd/cache/cache_backend_poll.c
+++ b/bin/varnishd/cache/cache_backend_poll.c
@@ -349,6 +349,7 @@ vbp_wrk_poll_backend(void *priv)
 
 		vt->req = VSB_data(vt->vsb);
 		vt->req_len = VSB_len(vt->vsb);
+		assert(vt->req_len > 0);
 
 		vbp_start_poke(vt);
 		vbp_poke(vt);