[Mailman-Developers] 3.0.0b1 fails bootstrap.py on Mountain Lion

[G B]

I initially posted this to mailman-users, but it was suggested that this would be a better list.

I'm installing Mailman for the first time, and chose to try the beta.  I'm installing on a Mountain Lion Server, that was cleanly installed.   I've since updated the OS to 10.8.1

I got as far as 'python bootstrap.py' and it failed immediately with the following traceback:

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Traceback (most recent call last):
 File "bootstrap.py", line 157, in <module>
   import pkg_resources
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/../../Extras/lib/python/pkg_resources.py", line 698, in <module>
   class Environment(object):
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/../../Extras/lib/python/pkg_resources.py", line 701, in Environment
   def __init__(self, search_path=None, platform=get_supported_platform(), python=PY_MAJOR):
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/../../Extras/lib/python/pkg_resources.py", line 99, in get_supported_platform
   plat = 'macosx-%s-%s' % ('.'.join(_macosx_vers()[:2]), m.group(3))
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/../../Extras/lib/python/pkg_resources.py", line 209, in _macosx_vers
   _cache.append(mac_ver()[0].split('.'))
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/platform.py", line 803, in mac_ver
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/platform.py", line 780, in _mac_ver_xml
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 78, in readPlist
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 406, in parse
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 418, in handleEndElement
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 452, in end_key
 File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 436, in getData
LookupError: unknown encoding: ascii
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FWIW, I can open an interactive Python session and execute "import pkg_resources"  from the command line without error.

Any ideas?

Thanks—
Greg