Issue a ban before the self-sharding vtc test.

Cached responses from other tests had been interfering with the test.

examples/self-sharding/verify.sh

@@ -11,6 +11,13 @@ LOCALPORT=${LOCALPORT:-8888}
 wait_until_ready app=varnish-ingress
 wait_until_configured app=varnish-ingress
 
+# Cached responses from previous tests occasionally interfere with the
+# current test, so issue a broad ban first.
+PODS=$(kubectl get pod -l app=varnish-ingress -o=name)
+for pod in ${PODS}; do
+    kubectl exec -t -c varnish ${pod} -- varnishadm -n /run/varnish-home ban obj.status == 200
+done
+
 kubectl port-forward svc/varnish-ingress ${LOCALPORT}:80 >/dev/null &
 trap 'kill $(jobs -p)' EXIT
 wait_for_port ${LOCALPORT}