OS X 10.9 XCode5.1升级后 安装Jekyll报错

报错如下：

sudo gem install jekyll
Password:
Building native extensions.  This could take a while...
ERROR:  Error installing jekyll:
    ERROR: Failed to build gem native extension.

    /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb
creating Makefile

make "DESTDIR=" clean

make "DESTDIR="
compiling porter.c
porter.c:359:27: warning: '&&' within '||' [-Wlogical-op-parentheses]
      if (a > 1 || a == 1 && !cvc(z, z->k - 1)) z->k--;
                ~~ ~~~~~~~^~~~~~~~~~~~~~~~~~~~
porter.c:359:27: note: place parentheses around the '&&' expression to silence this warning
      if (a > 1 || a == 1 && !cvc(z, z->k - 1)) z->k--;
                          ^
                   (                          )
1 warning generated.
compiling porter_wrap.c
linking shared-object stemmer.bundle
clang: error: unknown argument: '-multiply_definedsuppress' [-Wunused-command-line-argument-hard-error-in-future]
clang: note: this will be a hard error (cannot be downgraded to a warning) in the future
make: *** [stemmer.bundle] Error 1

make failed, exit code 2

Gem files will remain installed in /Library/Ruby/Gems/2.0.0/gems/fast-stemmer-1.0.2 for inspection.
Results logged to /Library/Ruby/Gems/2.0.0/extensions/universal-darwin-13/2.0.0/fast-stemmer-1.0.2/gem_make.out

This is due to Xcode 5.1 - its already reported as a bug to Ruby.

I found three different ways to fix the bug:

• Install using:

sudo ARCHFLAGS=-Wno-error=unused-command-line-argument-hard-error-in-future gem install jekyll

• Install Ruby 2.1.1. You can do this using brew install ruby (http://brew.sh/)
• Follow the instructions from http://stackoverflow.com/a/22340285/1270034 to remove the offending arg from rbconfig.