title: error bundle install postgresql: `mktmpdir': parent directory is world writable but not sticky
body: <p>I was trying to install rails with database postgresql and got an error:</p>
  
  <pre><code>Gem::Installer::ExtensionBuildError: ERROR: Failed to build gem native extension.
  
      /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby extconf.rb 
  checking for pg_config... yes
  Using config values from /usr/local/bin/pg_config
  *** 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=/System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/bin/ruby
          --with-pg
          --without-pg
          --enable-windows-cross
          --disable-windows-cross
          --with-pg-config
          --without-pg-config
          --with-pg_config
          --without-pg_config
          --with-pg-dir
          --without-pg-dir
          --with-pg-include
          --without-pg-include=${pg-dir}/include
          --with-pg-lib
          --without-pg-lib=${pg-dir}/
  /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/tmpdir.rb:92:in `mktmpdir': parent directory is world writable but not sticky (ArgumentError)
          from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:510:in `try_link0'
          from /System/Library/Frameworks/Ruby.framework/Versions/2.0/usr/lib/ruby/2.0.0/mkmf.rb:534:in `try_link'
          from extconf.rb:36:in `&lt;main&gt;'
  
  
  Gem files will remain installed in /tmp/bundler20150325-70824-ipx8vh/pg-0.18.1/gems/pg-0.18.1 for inspection.
  Results logged to /tmp/bundler20150325-70824-ipx8vh/pg-0.18.1/gems/pg-0.18.1/ext/gem_make.out
  An error occurred while installing pg (0.18.1), and Bundler cannot continue.
  Make sure that `gem install pg -v '0.18.1'` succeeds before bundling.
  </code></pre>
  
  <p>What can be done to fix this?</p>