Add notes about docstrings.
Merge Pack.keep support from Marc Brinkmann.
Fix syntax in Pack.keep docstring.
Add extra test for Pack.keep, copy pack so keep file is created in temp dir.
Fix typo pointed out by Rob.
Add test for write_tree_diff with a submodule.
Add submodule support in write_tree_diff.
Add more tests for write_object_diff, NEWS entry.
Merge support for submodules in write_tree_diff.
Fix compilation with XCode 4 and older versions of Python.
Release 0.7.1.
Start on 0.7.2.
Make read_refs private.
Hardcoding ARCHFLAGS breaks the build against fink's python

Fink's python is either i386 or amd64, but not universal. Setting ARCHFLAGS to the
empty string produces a successful build against both OS X python and fink python.
The modules will no longer be universal -- if that is an issue, we can change the
test to extract ARCHFLAGS from distutils.sysconfig and remove ppc if necessary.
Merge fix for building against Fink's Python from bcully.
Pass remote errors on as separate exception.
Report protocol activity when communicating over SSH.
Add message to assert.
Merge improved assert message.
Merge improvement of assertion message.