Bug#445985: environment proxy settings

[Tim Connors <reportbug@rather.puzzling.org>]

I strongly object to the proxy environment variable overriding that in the
conf file, because the apt.conf setting is more specific and is purely for
apt, and has likely been set by the sysadmin specifically to suite the
properties of debian packages -- large, and likely to be updated on a lot
of machines.  So if you are using apt-cacher, and all of your machines use
apt-cacher for the apt proxy, then you can set it as the proxy for apt
only, and everything else can keep using your squid proxy.

If the sysadmin (who is the only person running apt -- it's not like its
going to be carelessly run by someone who didn't deliberately set up their
system this way) wanted to use the same proxy as that contained in the
environment variable, then they wouldn't have set the proxy in the
apt.conf file in the first place.  But there are many reasons why he
wouldn't want to go the other way and remove his default setting just for
the sake of apt.