/etc/init.d/openvpn not starting automatically but can be started manually

Question

This is about init.d or Upstart init or something else, maybe, I think. But only OpenVPN is affected so far, after upgrading from Ubuntu 12.04 LTS to Ubuntu 12.10 on my VPS.

The problem is: OpenVPN daemon failed to start automatically on boot after upgrading. But start it manually with service openvpn start works just fine. Some info:

• Other services like sshd, bind9, postfix work fine.
• /etc/default/openvpn is fine.
• /etc/init.d is fine and I've already tried update-rc.d openvpn enable|remove|defaults. In vain.
• I did not touch /etc/openvpn before upgrading and everything there is fine.
• /var/log/boot.log shows Autostarting VPN 'foobar' but NOTHING happened actually.
• My OpenVPN log will not record ANYTHING during boot unless I start it manually. That to say, OpenVPN was not "starting... failing... exiting", but it did not get started at all. If it was "starting... failing... exiting", it would leave something in the log.

Here goes the most unbelievable fact: Even if I add service openvpn start in /etc/rc.local, it does not work. Furthing investigating revealed that whatever I added in /etc/rc.local, it did not run. This file is well ended with exit 0 and with execuatable bit. It seems "init" ignores it at all.

After working on this for a whole afternoon, goolging into many forums and StackExchange questions, I did not get it right... The only workaround I can think of is, after every reboot, log into the system, and run service openvpn start manually...

Could anyone help me get out this?

BTW, another delicated server with Ubuntu Server, upgrading from 12.04 LTS to 12.10 works fine with OpenVPN. Wird...