Here's a patch that adds support for xz compression:
http://svn.mandriva.com/cgi-bin/viewvc.cgi/packages/cooker/python/current/SOURCES/Python-2.6.1-distutils-xz-support.patch?view=log

Good idea !

are you able provide a unit test for the changes made into the two
commands ?

hmm, I'm unsure about how this should be done..


I guess such a test would belong in Lib/distutils/test_dist.py, but I'm
uncertain about how it should be done, ie. should it be a test for doing
'bdist', 'bdist_rpm' and 'sdist' for each of the formats supported? I
cannot seem to find any tests for the currently supported formats and
such tests would introduce dependencies on the tools used to compress
with these formats..

> I guess such a test would belong in Lib/distutils/test_dist.py

no, rather in test_bdist_rpm, test_sdist and so on,
but I can do it, it'll just take more time.

distutils2 uses tarfile now instead of external programs. Adding dependency on another bug.

FTR, the distutils2 repo is http://bitbucket.org/tarek/distutils2. distutils2.tests.support contains helper to create temp directories and run commands; see docstrings and example uses in the tests for more info.

distutils2/packaging now just uses the shutil functions.  I’ll make a patch for shutil after tarfile is updated.

This not-so-bad patch adds lzma compression support to the shutil functions, under the 'xztar' name.  Please review.

I should add that a doc update will be part of the next patch.

In parallel, I’ve also started updating packaging to add lzma support to the bdist command, but the situation is very disappointing: tarfile knows what format it supports, shutil has its own list, and packaging has a few duplicates too!  Ideally, tarfile should have an attribute to expose what compression formats are available, then shutil would reuse that, and packaging would just call shutil.  (I’m not even talking about the duplication in the doc.)  If you agree with the general idea, I’ll open reports to a) add the attribute to tarfile b) rework the (luckily internal) registries in shutil to stop being hard-coded c) remove packaging’s registries.

> This not-so-bad patch adds lzma compression support to the shutil functions, under the 'xztar' name.  Please review.

Functionally, the patch looks good to me. There are some docstrings that
should probably be updated, though:

- _make_tarball (the 'compress' argument)
- make_archive
- _unpack_tarfile
- unpack_archive


> Ideally, tarfile should have an attribute to expose what compression formats are available, then shutil would reuse that, and packaging would just call shutil.

+1