How difficult would it be to implement a pinning policy that only allowed packages released up until some timestamp:
-- /etc/apt/preferences --
Explanation: I want a system current as of some date.
Package: *
Pin: release a=stable <= 2014-03-18T12:00:00ZThis would be very useful in situations where you test out a staging system and want to upgrade a production system. In this case, you'd like to ensure that you only get the upgrades you have tested out in the staging environment.