我刚刚在一个已经包含2个Plone 4.3实例的文件夹中安装了一个新的plone 4.3实例，这两个实例都运行良好。当我尝试运行buildout时，我收到此错误：
Traceback (most recent call last):
File "bin/buildout", line 17, in <module>
import zc.buildout.buildout
File "/usr/local/Plone4.3/buildout-cache/eggs/zc.buildout-1.7.1-py2.7.egg/zc/buildout/buildout.py", line 40, in <module>
import zc.buildout.download
File "/usr/local/Plone4.3/buildout-cache/eggs/zc.buildout-1.7.1-py2.7.egg/zc/buildout/download.py", line 20, in <module>
from zc.buildout.easy_install import realpath
File "/usr/local/Plone4.3/buildout-cache/eggs/zc.buildout-1.7.1-py2.7.egg/zc/buildout/easy_install.py", line 31, in <module>
import setuptools.package_index
File "/usr/local/Plone4.3/Python-2.7/lib/python2.7/site-packages/distribute-0.6.35-py2.7.egg/setuptools/package_index.py", line 158, in <module>
sys.version[:3], require('distribute')[0].version
File "/usr/local/Plone4.3/buildout-cache/eggs/setuptools-0.6c11-py2.7.egg/pkg_resources.py", line 666, in require
continue # try the next older version of project
File "/usr/local/Plone4.3/buildout-cache/eggs/setuptools-0.6c11-py2.7.egg/pkg_resources.py", line 565, in resolve
pkg_resources.DistributionNotFound: distribute