title: Ruby can not find gem amongst even though it is in the list
body: <p>I am having a strange issue where when I try and run <code>vagrant up</code> the system can suddenly not find the json gem.  When I run vagrant up I get this message:</p>
  
  <pre><code>/usr/lib/ruby/vendor_ruby/1.8/rubygems/dependency.rb:247:in `to_specs': Could not find  json (~&gt; 1.5.1) amongst [Platform-0.4.0, archive-tar-minitar-0.5.2, builder-3.0.0,  bundler-1.1.5, childprocess-0.3.5, cucumber-1.2.1, diff-lcs-1.1.3, erubis-2.7.0, ffi-1.1.5, gemcutter-0.7.1, gherkin-2.11.2, git-1.2.5, hiera-0.3.0, hiera-json-0.3.0, hiera-puppet-0.3.0, highline-1.6.13, i18n-0.6.0, json-1.7.5, log4r-1.1.10, metaclass-0.0.1, mocha-0.12.3, net-scp-1.0.4, net-ssh-2.5.2, open4-1.3.0, popen4-0.1.2, progressbar-0.11.0, puppet-module-0.3.4, puppetlabs_spec_helper-0.3.0, rake-0.9.2.2, rspec-2.11.0, rspec-core-2.11.1, rspec-expectations-2.11.2, rspec-mocks-2.11.2, rspec-puppet-0.1.4, thor-0.16.0, vagrant-1.0.3, veewee-0.2.3, virtualbox-0.9.2] (Gem::LoadError)
          from /usr/lib/ruby/vendor_ruby/1.8/rubygems/specification.rb:771:in `activate_dependencies'
          from /usr/lib/ruby/vendor_ruby/1.8/rubygems/specification.rb:760:in `each'
          from /usr/lib/ruby/vendor_ruby/1.8/rubygems/specification.rb:760:in `activate_dependencies'
          from /usr/lib/ruby/vendor_ruby/1.8/rubygems/specification.rb:744:in `activate'
          from /usr/lib/ruby/vendor_ruby/1.8/rubygems.rb:1209:in `gem'
          from /usr/local/bin/vagrant:18
  </code></pre>
  
  <p>As you can see from the error above the json gem is clearly in the list, yet it will not recognize it.  I have searched for this issue and found many occurrences but most of the time the gem is not present in the amongst list.  I do not have ruby installed multiple times and the gem path is set.</p>
  
  <p>gem env</p>
  
  <p>RubyGems Environment:</p>
  
  <ul>
  <li>RUBYGEMS VERSION: 1.8.15</li>
  <li>RUBY VERSION: 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]</li>
  <li>INSTALLATION DIRECTORY: /var/lib/gems/1.8</li>
  <li>RUBY EXECUTABLE: /usr/bin/ruby1.8</li>
  <li>EXECUTABLE DIRECTORY: /usr/local/bin</li>
  <li>RUBYGEMS PLATFORMS:
  <ul>
  <li>ruby</li>
  <li>x86_64-linux</li>
  </ul></li>
  <li>GEM PATHS:
  <ul>
  <li>/var/lib/gems/1.8</li>
  <li>/home/adrian/.gem/ruby/1.8</li>
  </ul></li>
  <li>GEM CONFIGURATION:
  <ul>
  <li>:update_sources => true</li>
  <li>:verbose => true</li>
  <li>:benchmark => false</li>
  <li>:backtrace => false</li>
  <li>:bulk_threshold => 1000</li>
  </ul></li>
  <li>REMOTE SOURCES:
  <ul>
  <li><a href="http://rubygems.org/" rel="nofollow">http://rubygems.org/</a></li>
  </ul></li>
  </ul>
  
  <p>The installation directories are default on Ubuntu 12.04.</p>
  
  <p>gem list</p>
  
  <p><strong>* LOCAL GEMS *</strong></p>
  
  <pre><code>archive-tar-minitar (0.5.2)
  builder (3.0.0)
  bundler (1.1.5)
  childprocess (0.3.5)
  cucumber (1.2.1)
  diff-lcs (1.1.3)
  erubis (2.7.0)
  ffi (1.1.5)
  gemcutter (0.7.1)
  gherkin (2.11.2)
  git (1.2.5)
  hiera (0.3.0)
  hiera-json (0.3.0)
  hiera-puppet (0.3.0)
  highline (1.6.13)
  i18n (0.6.0)
  json (1.7.5)
  log4r (1.1.10)
  metaclass (0.0.1)
  mocha (0.12.3)
  net-scp (1.0.4)
  net-ssh (2.5.2)
  open4 (1.3.0)
  Platform (0.4.0)
  popen4 (0.1.2)
  progressbar (0.11.0)
  puppet-module (0.3.4)
  puppetlabs_spec_helper (0.3.0)
  rake (0.9.2.2)
  rspec (2.11.0)
  rspec-core (2.11.1)
  rspec-expectations (2.11.2)
  rspec-mocks (2.11.2)
  rspec-puppet (0.1.4)
  thor (0.16.0)
  vagrant (1.0.3)
  veewee (0.2.3)
  virtualbox (0.9.2)
  </code></pre>
  
  <p>As you can see the gem is in the installed list here to.  The environment variables <code>$GEM_HOME</code> and <code>$GEM_PATH</code> are not set.</p>
  
  <p>I have been trying to figure this one out but am currently at a loss.  Any help from a Ruby and/or Vagrant expert would be greatly appreciated.</p>