Bug#569917: Support base.tar.xz/bz2 as well as tgz

[Trent W. Buck]

Package: pbuilder
Version: 0.196
Severity: wishlist

pbuilder uses tar -z.  Maybe I can get a big space win for a small
cpu/memory loss by using tar --xz instead?  I hoped to simply

    s/tar -zcf/tar --xz -cf/
    s/tar -zxf/tar -xf/         # let tar auto-detect compression type

Unfortunately, in one or two places pbuilder passes the file to tar as
a stream, and tar can't auto-detect the compression type of streams.
A little refactoring is needed to support multiple compression types.

I don't have time to play further today, so I'm reporting this before
I forget about it.

-- System Information:
Debian Release: squeeze/sid
  APT prefers testing
  APT policy: (990, 'testing'), (500, 'unstable'), (1, 'experimental')
Architecture: amd64 (x86_64)

Kernel: Linux 2.6.24-23-openvz (SMP w/4 CPU cores)
Locale: LANG=en_AU.utf8, LC_CTYPE=en_AU.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages pbuilder depends on:
ii  cdebootstrap                  0.5.5      Bootstrap a Debian system
ii  coreutils                     8.4-1      GNU core utilities
ii  debconf [debconf-2.0]         1.5.28     Debian configuration management sy
ii  debianutils                   3.2.2      Miscellaneous utilities specific t
ii  debootstrap                   1.0.20     Bootstrap a basic Debian system
ii  wget                          1.12-1.1   retrieves files from the web

Versions of packages pbuilder recommends:
ii  devscripts                    2.10.61    scripts to make the life of a Debi
ii  fakeroot                      1.14.4-1   Gives a fake root environment
ii  sudo                          1.7.2p1-1  Provide limited super user privile

Versions of packages pbuilder suggests:
pn  cowdancer                     <none>     (no description available)
pn  gdebi-core                    <none>     (no description available)
pn  pbuilder-uml                  <none>     (no description available)

-- debconf information:
  pbuilder/rewrite: false
* pbuilder/mirrorsite: http://mirror.internode.on.net/pub/debian
* pbuilder/nomirror: