In APT preferences files the only allowed comments are lines that start
with `Explanation:`, commented lines that start with a # trigger a
myriad of interesting bugs. This is considered a feature of APT.
Because we're only ever writing a single file at a time with only a #
comment at the top we were getting away with this but it shouldn't be
there in the first place.
The default configuration we were writing for Debian was only working
for Squeeze, from Wheezy and onwards this wasn't working anymore. This
has to do with the fact that we should now be using Origins-Pattern
according to the unattended-upgrades docs. However, Ubuntu didn't
entirely get with the program yet...
This change reflects the defaults that unattended-upgrade installs on
every platform we support. In order to do so the unattended-upgrades
Debian archive for Squeeze, Wheezy, Lucid, Precise and Trusty were
downloaded and the default /etc/apt/apt.conf.d/50unattended-upgrades
checked for its content with regard to using Allow-Origins or
Origins-Pattern.
Fixes#277
The two forms of APT preferences records (general & specific) can now be
completely and not partially defined. All distribution properties can be passed
as resource parameters. This change is totally backward-compatible.
