python - ピップインストールエラー

Question

使用しようとするたびにpip、次のエラーが表示されます。

Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/2.7/bin/pip", line 5, in <module>
    from pkg_resources import load_entry_point
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pkg_resources.py", line 720, in <module>
    class Environment(object):
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pkg_resources.py", line 723, in Environment
    def __init__(self, search_path=None, platform=get_supported_platform(), python=PY_MAJOR):
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pkg_resources.py", line 109, in get_supported_platform
    plat = 'macosx-%s-%s' % ('.'.join(_macosx_vers()[:2]), m.group(3))
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pkg_resources.py", line 221, in _macosx_vers
    version = platform.mac_ver()[0]
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/platform.py", line 804, in mac_ver
    info = _mac_ver_xml()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/platform.py", line 781, in _mac_ver_xml
    pl = plistlib.readPlist(fn)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 78, in readPlist
    rootObject = p.parse(pathOrFile)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 406, in parse
    parser.ParseFile(fileobj)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 418, in handleEndElement
    handler()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 452, in end_key
    self.currentKey = self.getData()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/plistlib.py", line 436, in getData
    data = data.encode("ascii")
LookupError: no codec search functions registered: can't find encoding

実行しようとするsudo easy_install pipと、同じメッセージが表示されます。プロジェクト用pipに をインストールしようとしたときに、以前にこれを使用して受け取りました。virtualenvこれを引き起こした最近の更新やシステム変更は考えられません。以前にこのエラー メッセージに遭遇した人はいますか?