Bug#479800: exit BEFORE random_sleep() in cron script

[jidanni@jidanni.org]

Package: apt
Version: 0.7.12
File: /etc/cron.daily/apt

Please have /etc/cron.daily/apt check its variables and realize if it
has any work to do and if not EXIT BEFORE waiting around the
random_sleep()!

The user might not have the *luxury* of turning his computer on for
how long you *assume* he will.

Indeed, please FIRST check all the variables, and if all are 0, please
exit before even loading all those bash functions.

First task before all others: Are we to do any work at all? If no then
exit as early in the script as possible.

E.g., "a quick addition of the variables gives zero, exiting here".