varnishtest "vcl_backend_response abandon"

server s1 {
	rxreq
	txresp
} -start

varnish v1 -vcl+backend {
	sub vcl_backend_response {
		return (abandon);
	}
} -start

client c1 {
	txreq
	rxresp
	expect resp.status == 503
} -run
