How do I manually acknowledge the "System restart required" indicator?

[Derek Broughton]

Christofer C. Bell wrote:

> It turns out the answer is to delete /var/run/reboot-required.  This
> file is created when update-manager installs a new kernel, and removed
> during a reboot. 

I looked at this and though "how could it do that?".  Then realized it
doesn't, really.  Clever.  /var/run is created in a tmpfs filesystem.  So
after reboot, nothing gets "removed", it just doesn't exist anymore - which
is exactly what update-notifier wants.
-- 
derek