[master] 3c6c0917c varnishtest: Skip dispatch servers for -vcl+backend

[Dridi Boukelmoune]

commit 3c6c0917c1d781bcefe5f17da43ed0ecf8aa2310
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Wed Jun 22 16:05:46 2022 +0200

    varnishtest: Skip dispatch servers for -vcl+backend
    
    We don't want to list ephemeral backends when we load a new VCL after
    getting some s0 traffic.

diff --git a/bin/varnishtest/vtc_server.c b/bin/varnishtest/vtc_server.c
index 23606a1ac..783be0a2e 100644
--- a/bin/varnishtest/vtc_server.c
+++ b/bin/varnishtest/vtc_server.c
@@ -428,6 +428,9 @@ cmd_server_gen_vcl(struct vsb *vsb)
 
 	AZ(pthread_mutex_lock(&server_mtx));
 	VTAILQ_FOREACH(s, &servers, list) {
+		if (s->sock < 0 && s->fd >= 0) /* dispatch instance */
+			continue;
+
 		if (*s->listen != '/')
 			VSB_printf(vsb,
 				   "backend %s { .host = \"%s\"; "