Supply reasonable defaults for error code / reason.

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@2161 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/cache_vrt.c

@@ -56,8 +56,8 @@ VRT_error(struct sess *sp, unsigned code, const char *reason)
 
 	CHECK_OBJ_NOTNULL(sp, SESS_MAGIC);
 	WSL(sp->wrk, SLT_Debug, 0, "VCL_error(%u, %s)", code, reason);
-	sp->err_code = code;
-	sp->err_reason = reason;
+	sp->err_code = code ? code : 503;
+	sp->err_reason = reason ? reason : http_StatusMessage(sp->err_code);
 }
 
 /*--------------------------------------------------------------------*/