Bail if the cli pipe is not ready

git-svn-id: http://www.varnish-cache.org/svn/trunk/varnish-cache@673 d4fa192b-c00b-0410-8231-f00ffab90ce4

bin/varnishd/mgt_cli.c

@@ -178,6 +178,8 @@ mgt_cli_askchild(unsigned *status, char **resp, const char *fmt, ...)
 	va_list ap;
 	unsigned u;
 
+	if (cli_i < 0|| cli_o < 0)
+		return (CLIS_CANT);
 	va_start(ap, fmt);
 	i = vasprintf(&p, fmt, ap);
 	va_end(ap);