Ned> Are you sure you're not really using the MacPorts python?  What's
    Ned> the value of sys.executable?

Yup, pretty sure. :-)  Here it is run from my hg sandbox:

    % pwd
    /Users/skip/src/hgpython/2.7
    % ./python.exe
    Python 2.7.1 (r271:86832, Feb  2 2011, 06:56:19) 
    [GCC 4.0.1 (Apple Inc. build 5493)] on darwin
    Type "help", "copyright", "credits" or "license" for more information.
    >>> import sys
    >>> sys.executable
    '/Users/skip/src/hgpython/2.7/python.exe'
    >>> sys.path
    ['/Users/skip/misc/python/python2', '/Users/skip/misc/python', '', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-darwin', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plat-mac/lib-scriptpackages', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-tk', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/lib-dynload', '/Users/skip/.local/lib/python2.7/site-packages', '/opt/local/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages']

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