无法使用pip在MacOSX上安装模拟包

Question

当我这样做时出现以下错误＆gt; pip在virtualenv中安装模拟

(test)mystogans-mac:clean_arch resnet$ pip install --upgrade --force-reinstall mock
Downloading/unpacking mock
  Downloading mock-1.1.3.tar.gz (70kB): 70kB downloaded
  Running setup.py egg_info for package mock
    Traceback (most recent call last):
      File "<string>", line 16, in <module>
      File "/Users/resnet/Documents/workspace/CodePython/clean_arch/test/build/mock/setup.py", line 10, in <module>
        setuptools_installed = StrictVersion(setuptools.version.__version__)
    AttributeError: 'module' object has no attribute 'version'
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):
  File "<string>", line 16, in <module>
  File "/Users/resnet/Documents/workspace/CodePython/clean_arch/test/build/mock/setup.py", line 10, in <module>

setuptools_installed = StrictVersion(setuptools.version.__version__)

AttributeError: 'module' object has no attribute 'version'.