pbuilder-dist: use APTCACHE in pbulderrc if specified

[Nobuto Murata]

This is a feature request to override "--aptcache" from APTCACHE in pbuilderrc (related Bug #956903).

I would like to user empty APTCACHE value to turn off caching as I have another proxy to cache packages. I don't want to have duplicate cache.

pbuilderrc(5)
> Specify the location that the packages downloaded by apt should
> be cached. Setting this value to "" will cause caching to be
> turned off.

APTCACHE in pbuilderrc seems ignored and default value "~/aptcache/ubuntu" is actually used.

$ pbuilder-dist trusty create --debug-echo
pbuilder-dist: Warning: Distribution data outdated. Please check for an update for distro-info-data. See /usr/share/doc/distro-info-data/README.Debian for details.
['sudo', 'HOME=/home/nobuto', 'ARCHITECTURE=amd64', 'DISTRIBUTION=trusty', 'ARCH=amd64', 'DIST=trusty', 'DEB_BUILD_OPTIONS=', 'pbuilder', '--create', '--distribution', 'trusty', '--buildresult', '/home/nobuto/pbuilder/trusty_result', '--basetgz', '/home/nobuto/pbuilder/trusty-base.tgz', '--logfile', '/home/nobuto/pbuilder/trusty_result/last_operation.log', '--mirror', 'http://archive.ubuntu.com/ubuntu', '--othermirror', 'deb http://archive.ubuntu.com/ubuntu trusty-proposed main restricted universe multiverse', '--aptcache', '/home/nobuto/pbuilder/aptcache/ubuntu', '--components', 'main restricted universe multiverse']

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubuntu-dev-tools 0.153
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CurrentDesktop: Unity
Date: Fri Apr 18 15:45:21 2014
EcryptfsInUse: Yes
InstallationDate: Installed on 2013-10-15 (184 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Beta amd64 (20131014)
PackageArchitecture: all
SourcePackage: ubuntu-dev-tools
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Nathan Rennie-Waldock (nathan-renniewaldock)]

Agreed. --aptcache needs to not be forced as many of us are running apt-cacher(-ng), so it just results in there being 2 copies of packages on disk. Maybe pbuilder-dist should source .pbuilderrc and prefer some of those settings?