title: ERROR: Failed to build gem native extension on rubygem installation
body: <p>While trying to do "bundle install",  I receive error message below </p>
  
  <blockquote>
    <p>environment = <strong>OSX 10.9.4</strong>, <strong>rbenv 0.4.0</strong>,
    <strong>ruby 2.1.2</strong>,
    <strong>Homebrew 0.9.5</strong></p>
  </blockquote>
  
  <pre><code>Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
      /Users/hirotakagotanda/.rbenv/versions/2.1.2/bin/ruby extconf.rb 
  *** extconf.rb failed ***
  Could not create Makefile due to some reason, probably lack of necessary
  libraries and/or headers.  Check the mkmf.log file for more details.  You may
  need configuration options.
  
  Provided configuration options:
      --with-opt-dir
      --without-opt-dir
      --with-opt-include
      --without-opt-include=${opt-dir}/include
      --with-opt-lib
      --without-opt-lib=${opt-dir}/lib
      --with-make-prog
      --without-make-prog
      --srcdir=.
      --curdir
      --ruby=/Users/hirotakagotanda/.rbenv/versions/2.1.2/bin/ruby
  /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in `stat': No such file or directory @ rb_file_s_stat - ./212/ruby_debug.h (Errno::ENOENT)
      from /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/2.1.0/fileutils.rb:1573:in `block in fu_each_src_dest'
      from /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/2.1.0/fileutils.rb:1587:in `fu_each_src_dest0'
      from /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/2.1.0/fileutils.rb:1571:in `fu_each_src_dest'
      from /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/2.1.0/fileutils.rb:399:in `cp'
      from extconf.rb:83:in `block in &lt;main&gt;'
      from extconf.rb:82:in `each'
      from extconf.rb:82:in `&lt;main&gt;'
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/gems/debugger-1.6.6 for inspection.
  Results logged to /Users/hirotakagotanda/.rbenv/versions/2.1.2/lib/ruby/gems/2.1.0/extensions/x86_64-darwin-13/2.1.0-static/debugger-1.6.6/gem_make.out
  An error occurred while installing debugger (1.6.6), and Bundler cannot continue.
  Make sure that `gem install debugger -v '1.6.6'` succeeds before bundling.
  </code></pre>
  
  <p>Could anyone please provide me solution, I have been misfortunate to find out any...</p>