require setuptools >= 0.6c6 on cygwin, and >= 0.6a9 on other platforms

Earlier I tried 0.6a9 (which comes in .deb format on Dapper) and something
didn't work, so I raised it to 0.6c3.  However, I didn't make a note of what
failed, and so now I'm hoping that what failed was cygwin-specific.  Anyway,
everyone look out for setuptools compatibility problems on the your favorite
platform (and I'll check the buildslaves), and we'll raise the required version
as little as possible and only on the problematic platform.

README

@@ -72,12 +72,13 @@ gcc make python-dev python-twisted python-nevow python-pyopenssl".
 
  + Python setuptools (build and distribution tool)
 
-   Note: The build process will automatically download and install
-   setuptools if it is not present.  However, if an old, incompatible
-   version of setuptools (< v0.6c6) is present, then the build will fail.
-   Therefore, if the build fails due to setuptools not being compatible,
-   you can either upgrade or uninstall your version of setuptools and try
-   again.
+   Note: The build process will automatically download and install setuptools
+   if it is not present.  However, if an old, incompatible version of
+   setuptools is present (< v0.6c6 on Cygwin, or < v0.6a9 on other
+   platforms), then the build will fail.
+
+   So if the build fails due to setuptools not being compatible, you can
+   either upgrade or uninstall your version of setuptools and try again.
 
    http://peak.telecommunity.com/DevCenter/EasyInstall#installation-instructions
 

src/simplejson/setup.py

@@ -1,7 +1,11 @@
 #!/usr/bin/env python
 
 import ez_setup
-ez_setup.use_setuptools(min_version="0.6c6")
+if 'cygwin' in sys.platform.lower():
+    min_version='0.6c6'
+else:
+    min_version='0.6a9'
+ez_setup.use_setuptools(min_version=min_version)
 
 from setuptools import setup, find_packages, Extension, Feature
 from distutils.command.build_ext import build_ext

src/zfec/setup.py

@@ -20,7 +20,12 @@
 # http://allmydata.com/.
 
 from ez_setup import use_setuptools
-use_setuptools(min_version='0.6c6')
+import sys
+if 'cygwin' in sys.platform.lower():
+    min_version='0.6c6'
+else:
+    min_version='0.6a9'
+use_setuptools(min_version=min_version)
 
 from setuptools import Extension, find_packages, setup