- Quote the 'spec' argument, as in the case of installing an egg from
  the buildout-cache, if the filename contains spaces it would fail

AttributeError:
Buildout instance has no attribute '_logger' 

- 1.0.2 release

This change reduces test failures on my current platform from 48 to 3.
I hope it doesn't break zc.buildout on any other platform.

- further rmtree fixes for Windows

  Gottfried Ganssauge) (ajung)

- allowed to interpolate variables with the environment

- make sure the environment is cleaned

Remove gibberish paragraph from variable substitution section (was this ever true?), correct next paragraph to reflect current example.

The 'if not self._valid(ref)' branch is *always* executed because ref still includes the ${} substitution marker around it. Update the _valid regular expression to include the markers, shaving off 4 tests for every substitution.

with PyPI URLs (the old ones no more working)

version #. Grrrr.

selecting Python tests without Python 2.3 available, since I've lost
Python 2.3 in my upgrade to Mac OS X 2.5. :(

extra uses.

easier to test multiple versions at once.

1.0 coming soon. :)

zc.sourcedistribution.

leading to test failures.  The change also caused buildout to fail
with Python 2.3, which lacks a set builtin.