title: Gem is installed but it is not found by bundle show
body: <p>I'm having trouble getting the pg gem working with my rails app.</p>
  
  <p>When I do a sudo bundle install I get:</p>
  
  <pre><code>Using rake (10.0.4)
  Using i18n (0.6.4)
  Using multi_json (1.7.2)
  Using activesupport (3.2.8)
  Using builder (3.0.4)
  Using activemodel (3.2.8)
  Using erubis (2.7.0)
  Using journey (1.0.4)
  Using rack (1.4.5)
  Using rack-cache (1.2)
  Using rack-test (0.6.2)
  Using hike (1.2.1)
  Using tilt (1.3.6)
  Using sprockets (2.1.3)
  Using actionpack (3.2.8)
  Using mime-types (1.22)
  Using polyglot (0.3.3)
  Using treetop (1.4.12)
  Using mail (2.4.4)
  Using actionmailer (3.2.8)
  Using arel (3.0.2)
  Using tzinfo (0.3.37)
  Using activerecord (3.2.8)
  Using activeresource (3.2.8)
  Using coffee-script-source (1.6.2)
  Using execjs (1.4.0)
  Using coffee-script (2.2.0)
  Using rack-ssl (1.3.3)
  Using json (1.7.7)
  Using rdoc (3.12.2)
  Using thor (0.18.1)
  Using railties (3.2.8)
  Using coffee-rails (3.2.2)
  Using jquery-rails (2.2.1)
  Using pg (0.15.0)
  Using bundler (1.1.5)
  Using rails (3.2.8)
  Using sass (3.2.7)
  Using sass-rails (3.2.6)
  Using uglifier (1.3.0)
  </code></pre>
  
  <p>However, when I do a 'bundle show' for any gem, I get:</p>
  
  <pre><code>Could not find pg-0.15.0 in any of the sources
  </code></pre>
  
  <p>Additionally, when I do any rake command, I get:</p>
  
  <pre><code>/usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/spec_set.rb:90:in `block in materialize': Could not find pg-0.15.0 in any of the sources (Bundler::GemNotFound)
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/spec_set.rb:83:in `map!'
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/spec_set.rb:83:in `materialize'
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/definition.rb:127:in `specs'
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/environment.rb:27:in `specs'
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.6/lib/rubygems-bundler/noexec.rb:41:in `candidate?'
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.6/lib/rubygems-bundler/noexec.rb:60:in `setup'
          from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/rubygems-bundler-1.0.6/lib/rubygems-bundler/noexec.rb:75:in `&lt;top (required)&gt;'
          from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `require'
          from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:60:in `rescue in require'
          from /usr/local/rvm/rubies/ruby-1.9.3-p194/lib/ruby/site_ruby/1.9.1/rubygems/custom_require.rb:35:in `require'
          from /usr/local/rvm/gems/ruby-1.9.3-p194/bin/ruby_noexec_wrapper:9:in `&lt;main&gt;'
  </code></pre>
  
  <p>I suspect that it has something to do with RVM and what version of Ruby I'm using since I recently changed to 1.9.3. Any ideas?</p>