title: Why does `gem install` work but not `bundle install`
body: <p>In my project when I ran <code>bundle install</code> I got the following error:</p>
  
  <pre><code>An error occurred while installing nokogiri (1.6.1), and Bundler cannot continue.
  Make sure that `gem install nokogiri -v '1.6.1'` succeeds before bundling.
  </code></pre>
  
  <p>So I did try </p>
  
  <pre><code> gem install nokogiri -v '1.6.1'
  </code></pre>
  
  <p>This did work. Now of course this should make me happy, but I am wondering now, what exactly did the trick, so I could install the gem and now <code>bundle install</code> also succeeds.</p>
  
  <p>I am running Mac OSX 10.9.2. </p>
  
  <p>This is my Log when I first ran <code>bundle install</code></p>
  
  <pre><code>Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
      /Users/me/.rvm/rubies/ruby-1.9.3-p545/bin/ruby extconf.rb --with-xml2-dir=/usr --with-xslt-dir=/opt/local --with-iconv-dir=/opt/local
  Extracting libxml2-2.8.0.tar.gz into tmp/x86_64-apple-darwin13.1.0/ports/libxml2/2.8.0... OK
  Running 'configure' for libxml2 2.8.0... OK
  Running 'compile' for libxml2 2.8.0... OK
  Running 'install' for libxml2 2.8.0... OK
  Activating libxml2 2.8.0 (from /Users/me/.rvm/gems/ruby-1.9.3-p545/gems/nokogiri-1.6.1/ports/x86_64-apple-darwin13.1.0/libxml2/2.8.0)...
  Extracting libxslt-1.1.26.tar.gz into tmp/x86_64-apple-darwin13.1.0/ports/libxslt/1.1.26... OK
  Running 'configure' for libxslt 1.1.26... OK
  Running 'compile' for libxslt 1.1.26... OK
  Running 'install' for libxslt 1.1.26... OK
  Activating libxslt 1.1.26 (from /Users/me/.rvm/gems/ruby-1.9.3-p545/gems/nokogiri-1.6.1/ports/x86_64-apple-darwin13.1.0/libxslt/1.1.26)...
  checking for libxml/parser.h... no
  -----
  libxml2 is missing.  please visit http://nokogiri.org/tutorials/installing_nokogiri.html for help with installing dependencies.
  -----
  *** 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
      --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/me/.rvm/rubies/ruby-1.9.3-p545/bin/ruby
      --with-zlib-dir
      --without-zlib-dir
      --with-zlib-include
      --without-zlib-include=${zlib-dir}/include
      --with-zlib-lib
      --without-zlib-lib=${zlib-dir}/lib
      --with-iconv-dir
      --with-iconv-include
      --without-iconv-include=${iconv-dir}/include
      --with-iconv-lib
      --without-iconv-lib=${iconv-dir}/lib
      --with-xml2-dir
      --with-xml2-include
      --without-xml2-include=${xml2-dir}/include
      --with-xml2-lib
      --without-xml2-lib=${xml2-dir}/lib
      --with-xslt-dir
      --with-xslt-include
      --without-xslt-include=${xslt-dir}/include
      --with-xslt-lib
      --without-xslt-lib=${xslt-dir}/lib
      --with-libxslt-config
      --without-libxslt-config
      --with-pkg-config
      --without-pkg-config
      --with-libxml-2.0-config
      --without-libxml-2.0-config
      --with-libiconv-config
      --without-libiconv-config
  
  extconf failed, exit code 1
  
  Gem files will remain installed in /Users/me/.rvm/gems/ruby-1.9.3-p545/gems/nokogiri-1.6.1 for inspection.
  Results logged to /Users/me/.rvm/gems/ruby-1.9.3-p545/extensions/x86_64-darwin-13/1.9.1/nokogiri-1.6.1/gem_make.out
  </code></pre>