jessie: not always an /etc/inittab...

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>

lib/debian-finish.sh

@@ -48,6 +48,7 @@ if [ ! "x${conf_smart_uboot}" = "xenable" ] ; then
 	fi
 fi
 
+if [ -f /etc/inittab ] ; then
 if [ "x${serial_tty}" != "x" ] ; then
 		cp /etc/inittab /boot/uboot/backup/inittab
 		serial_num=$(echo -n "${serial_tty}"| tail -c -1)
@@ -60,8 +61,9 @@ if [ "x${serial_tty}" != "x" ] ; then
 
 		#Convert ttyS0 9600 vt100 -> ${serial_tty} 115200 vt102
 		sed -i -e "s/ttyS0 9600 vt100/${serial_tty} 115200 vt102/g" /etc/inittab
-else
+	else
 		echo "WARN: [serial_tty] was undefined..." >> /var/log/netinstall.log
+	fi
 fi
 
 if [ "x${boot_fstype}" = "xfat" ] ; then