升级 El Capitan 之后遇到的第一个兼容性问题， pip install wand 坏掉了

$ sudo pip install wand
Downloading/unpacking wand
  Downloading Wand-0.4.1.tar.gz (61kB): 61kB downloaded
  Running setup.py (path:/private/tmp/pip_build_root/wand/setup.py) egg_info for package wand
    Traceback (most recent call last):
      File "<string>", line 17, in <module>
      File "/private/tmp/pip_build_root/wand/setup.py", line 8, in <module>
        from wand.version import VERSION
      File "wand/version.py", line 45, in <module>
        from .api import libmagick, library
      File "wand/api.py", line 1295, in <module>
        libc = ctypes.cdll.LoadLibrary('libc.dylib')
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py", line 443, in LoadLibrary
        return self._dlltype(name)
      File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py", line 365, in __init__
        self._handle = _dlopen(self._name, mode)
    OSError: dlopen(libc.dylib, 6): image not found
    Complete output from command python setup.py egg_info:
    Traceback (most recent call last):

  File "<string>", line 17, in <module>

  File "/private/tmp/pip_build_root/wand/setup.py", line 8, in <module>

    from wand.version import VERSION

  File "wand/version.py", line 45, in <module>

    from .api import libmagick, library

  File "wand/api.py", line 1295, in <module>

    libc = ctypes.cdll.LoadLibrary('libc.dylib')

  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py", line 443, in LoadLibrary

    return self._dlltype(name)

  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/ctypes/__init__.py", line 365, in __init__

    self._handle = _dlopen(self._name, mode)

OSError: dlopen(libc.dylib, 6): image not found