boot_command appears to lose vnc connection on guest reboot

[kevemueller]

I have a boot_command that spans a guest reboot. Basically it is performing an installation, restarting the machine, awaiting it to come back up and continuing after it initialized its state. The work cannot be done before reboot as the environment for that is not yet set-up.

Despite generous <wait> applied, the boot_command cannot complete. One indication that it is VNC related is that the console is no longer locked exclusively in XO, meaning while packer is still typing, the rebooted guest's console is already visible in XO. A similar packer configuration against vsphere runs through, i.e. there the boot_command is continued with the rebooted guest.