RFR / ITM: b2 p-u branch

["Adam D. Barratt" <adam@adam-barratt.org.uk>]

Hi,

As has been mentioned a few times in the recent (and not so recent)
past, including in Niels's blog, I've been working on a branch of
britney2 which attempts to make some of the code more "objecty" and more
natural to follow and maintain.

I think it's time that we looked at merging it in to master, unless
anyone finds any major issues with it, not least because it means I can
start making unrelated changes without duplicating them across the
branches.  Please consider this a request for review in anticipation of
that merge. :-)

The current state of the branch can be found at
http://anonscm.debian.org/gitweb/?p=users/adsb/b2/.git;a=summary

It currently passes seven more tests from the test suite than the master
branch - or, if you prefer, fails 50% less.  All of the differences
appear to be related to the precise details of how the list of packages
to iterate in the main run (i.e. self.upgrade_me) is constituted; this
either means there are corner cases where the current implementation is
sub-optimal, or that I've broken it - hopefully the former, of course.

Cheers,

Adam