Bug#864681: Apt ux improvment: retry on lock aquisition

[David Britton <david.britton@canonical.com>]

Package: apt
Version: 1.4.6


In working on: https://bugs.launchpad.net/cloud-init/+bug/1693361, as
well as many other pieces of software throughout my time working with
Ubuntu, the lack of a retry on lock acquisition is certainly an area
where apt and libapt could improve.

As it stands, all client applications that interact with Apt are
burdened with similar boilerplate concepts of blind retries with backoff
algorithms.

A single command line with more advanced config settings would probably
satisfy the bulk of use cases.

  apt --retry-lock-timeout 30

With NEVER being the default (forever), and duration to retry in minutes as
the accepted parameter, 0 meaning, don't retry, or timeout immediately.


-- 
David Britton <david.britton@canonical.com>