pip install XXX で OSErrorが出てしまった時の対処。(メモ)

使用OSはOSXです。
入力コマンド

$ pip install パッケージ名

エラー内容

Exception:
Traceback (most recent call last):
  File "/Library/Python/2.7/site-packages/pip-7.1.2-py2.7.egg/pip/basecommand.py", line 211, in main
    status = self.run(options, args)
  File "/Library/Python/2.7/site-packages/pip-7.1.2-py2.7.egg/pip/commands/install.py", line 311, in run
    root=options.root_path,
  File "/Library/Python/2.7/site-packages/pip-7.1.2-py2.7.egg/pip/req/req_set.py", line 640, in install
    requirement.uninstall(auto_confirm=True)
  File "/Library/Python/2.7/site-packages/pip-7.1.2-py2.7.egg/pip/req/req_install.py", line 716, in uninstall
    paths_to_remove.remove(auto_confirm)
  File "/Library/Python/2.7/site-packages/pip-7.1.2-py2.7.egg/pip/req/req_uninstall.py", line 125, in remove
    renames(path, new_path)
  File "/Library/Python/2.7/site-packages/pip-7.1.2-py2.7.egg/pip/utils/__init__.py", line 315, in renames
    shutil.move(old, new)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 302, in move
    copy2(src, real_dst)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 131, in copy2
    copystat(src, dst)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/shutil.py", line 103, in copystat
    os.chflags(dst, st.st_flags)
OSError: [Errno 1] Operation not permitted: '/var/folders/tx/22hzdby50gg4cbnzx_39c5dm0000gn/T/pip-ziJ8uF-uninstall/System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python/numpy-1.8.0rc1-py2.7.egg-info'

解決方法

はじめにpipをアップグレードしておく。これは念のためでしなくてもいい。

pip install --upgrade pip

そのあと次のコマンドでインストールできるはず。パッケージ名は適宜書き換えてください。

sudo pip install パッケージ名 --upgrade --ignore-installed six