brew postinstall python（2.7.13）：[Errno 13]权限被拒绝

我在OS X 10.11.6上。我今天更新并升级了brew。在那之后，pip没有工作。看起来好像在升级期间未安装。完成升级后，我看到了警告：

Warning: The post-install step did not complete successfully You can try again using brew postinstall python

所以我跑了brew postinstall python，然后遇到了错误：

error: [Errno 13] Permission denied: '/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py'

他们在这篇文章中说：

由于error: could not delete '/usr/local/lib/python2.7/site-packages/pip/__init__.py': Permission denied.手动删除该文件，然后运行brew postinstall python再次修复了该问题，因此安装后步骤未成功完成。

所以我认为解决方法是相同的，/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py'因此我手动删除了

$ ls /usr/local/lib/python2.7/site-packages/pkg_resources/
_vendor extern

我又跑了brew postinstall python一次，但现在我得到了：

...
copying build/lib/easy_install.py -> /usr/local/lib/python2.7/site-packages
copying build/lib/pkg_resources/__init__.py -> /usr/local/lib/python2.7/site-packages/pkg_resources
error: [Errno 13] Permission denied: '/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py'` 

我通过使用安装pip找到了“解决办法” easy_install：

sudo easy_install pip

现在一切似乎都正常了。但是，我有两个问题：

1. 我是否因手动删除而搞砸了'/usr/local/lib/python2.7/site-packages/pkg_resources/__init__.py'？

2. 什么[Errno 13] Permission denied时候解决brew postinstall python？

如果有什么用，这里是我brew config和brew doctor今天发生的一切之后的输出：

$ brew config
HOMEBREW_VERSION: 1.1.6
ORIGIN: https://github.com/Homebrew/brew
HEAD: 619791e83d2781dca1b675e20249a8aebe085c7c
Last commit: 6 days ago
Core tap ORIGIN: https://github.com/Homebrew/homebrew-core
Core tap HEAD: 5ce01ec9c8b9958e2d9a7791e4d4e2aa0bf4fd8f
Core tap last commit: 89 minutes ago
HOMEBREW_PREFIX: /usr/local
HOMEBREW_REPOSITORY: /usr/local/Homebrew
HOMEBREW_CELLAR: /usr/local/Cellar
HOMEBREW_BOTTLE_DOMAIN: https://homebrew.bintray.com
CPU: octa-core 64-bit haswell
Homebrew Ruby: 2.0.0-p648
Clang: 8.0 build 800
Git: 2.10.1 => /Applications/Xcode.app/Contents/Developer/usr/bin/git
Perl: /usr/bin/perl
Python: /usr/local/bin/python => /usr/local/Cellar/python/2.7.13/Frameworks/Python.framework/Versions/2.7/bin/python2.7
Ruby: /usr/bin/ruby => /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
Java: 1.8.0_91
macOS: 10.11.6-x86_64
Xcode: 8.2.1
CLT: 8.2.0.0.1.1480973914
X11: 2.7.11 => /opt/X11

$ brew doctor
Warning: Unbrewed dylibs were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected dylibs:
  /usr/local/lib/libtcl8.6.dylib
  /usr/local/lib/libtk8.6.dylib

Warning: Unbrewed header files were found in /usr/local/include.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected header files:
  /usr/local/include/fakemysql.h
  /usr/local/include/fakepq.h
  /usr/local/include/fakesql.h
  /usr/local/include/itcl.h
  /usr/local/include/itcl2TclOO.h
  /usr/local/include/itclDecls.h
  /usr/local/include/itclInt.h
  /usr/local/include/itclIntDecls.h
  /usr/local/include/itclMigrate2TclCore.h
  /usr/local/include/itclTclIntStubsFcn.h
  /usr/local/include/mysqlStubs.h
  /usr/local/include/odbcStubs.h
  /usr/local/include/pqStubs.h
  /usr/local/include/tcl.h
  /usr/local/include/tclDecls.h
  /usr/local/include/tclOO.h
  /usr/local/include/tclOODecls.h
  /usr/local/include/tclPlatDecls.h
  /usr/local/include/tclThread.h
  /usr/local/include/tclTomMath.h
  /usr/local/include/tclTomMathDecls.h
  /usr/local/include/tdbc.h
  /usr/local/include/tdbcDecls.h
  /usr/local/include/tdbcInt.h
  /usr/local/include/tk.h
  /usr/local/include/tkDecls.h
  /usr/local/include/tkPlatDecls.h

Warning: Unbrewed .pc files were found in /usr/local/lib/pkgconfig.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected .pc files:
  /usr/local/lib/pkgconfig/tcl.pc
  /usr/local/lib/pkgconfig/tk.pc

Warning: Unbrewed static libraries were found in /usr/local/lib.
If you didn't put them there on purpose they could cause problems when
building Homebrew formulae, and may need to be deleted.

Unexpected static libraries:
  /usr/local/lib/libtclstub8.6.a
  /usr/local/lib/libtkstub8.6.a