title: Bundler: "Could not find bson-1.4.0 in any of the sources"
body: <p>I'm trying to do a <code>bundle install</code> but I'm getting the error 
  <code>Could not find bson-1.4.0 in any of the sources</code>.
  I believe bson-1.4.0 is a requirement for mongoid ~> 2.0 which is in my Gemfile.</p>
  
  <p>When I try <code>gem install -v 1.4.0 bson</code>, I get the error</p>
  
  <pre><code>ERROR:  Could not find a valid gem 'bson' (= 1.4.0), here is why:
            Found bson (1.4.0), but was for platform jruby
  </code></pre>
  
  <p>the bundle install works fine on my development machine (running OSX 10.6.8), but I'm having this problem on a 64-Bit Amazon EC2 instance.</p>
  
  <p>If I try requesting an earlier version, then do a <code>bundle update</code>, I get the error</p>
  
  <p><code>Could not find gem 'bson (= 1.4.0) x86-mingw32', which is required by gem 'mongo (~&gt; 1.3) x86-mingw32', in any of the sources.</code></p>
  
  <p>could it be because of it being 64bit? Any possible workarounds?</p>
  
  <p>running rails 3.0.10</p>