title: Mongoid fails on ruby 1.9.3
body: <p>So I'm playing around with mongo stuffs. Created a new heroku app, added a mongolab option to it, but every mongoid method fails.</p>
  
  <p>I googled around, and it looks like this issue was common with ruby prior to 1.9.3, but I'm running 1.9.3.</p>
  
  <p>Here's the simplest failing sample:</p>
  
  <pre><code>require 'sinatra'
  require 'mongoid'
  require 'json'
  require "sinatra/reloader" if development?
  
  Mongoid.load!("mongoid.yml")
  
  class Company
      include Mongoid::Document
  
      field :code, type: String
      field :sector, type: String
      field :share_id, type: Integer
      field :jse_code, type: Integer
  end
  
  get '/' do
      "Hello" 
  end
  
  get '/company' do
      Company.exists?
  end
  </code></pre>
  
  <p>Wether I run this locally (against the mongolab db) or on heroku, I get the same kind of error:</p>
  
  <pre><code>12:22:33 web.1  | NoMethodError - undefined method `match' for nil:NilClass:
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions/mongo_uri.rb:49:in `initialize'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:103:in `new'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:103:in `parse'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:62:in `create_session'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions/factory.rb:43:in `default'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:109:in `default'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:378:in `__session__'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:213:in `mongo_session'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/sessions.rb:157:in `collection'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/contextual/mongo.rb:216:in `initialize'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/contextual.rb:47:in `new'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/contextual.rb:47:in `create_context'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/contextual.rb:30:in `context'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/contextual.rb:20:in `rescue in exists?'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/contextual.rb:18:in `exists?'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/mongoid-3.0.13/lib/mongoid/finders.rb:43:in `exists?'
  12:22:33 web.1  |   app.rb:22:in `block in &lt;main&gt;'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:1265:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:1265:in `block in compile!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `[]'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `block (3 levels) in route!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:851:in `route_eval'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:835:in `block (2 levels) in route!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:872:in `block in process_route'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:870:in `catch'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:870:in `process_route'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:834:in `block in route!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:833:in `each'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:833:in `route!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:936:in `dispatch!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:769:in `block in call!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `block in invoke'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `catch'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:921:in `invoke'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:769:in `call!'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:755:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-protection-1.2.0/lib/rack/protection/path_traversal.rb:16:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-protection-1.2.0/lib/rack/protection/json_csrf.rb:17:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-protection-1.2.0/lib/rack/protection/base.rb:47:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-protection-1.2.0/lib/rack/protection/xss_header.rb:22:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-1.4.1/lib/rack/logger.rb:15:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-1.4.1/lib/rack/commonlogger.rb:20:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:136:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:129:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-1.4.1/lib/rack/head.rb:9:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/rack-1.4.1/lib/rack/methodoverride.rb:21:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/showexceptions.rb:21:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:99:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:1389:in `block in call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:1471:in `synchronize'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/sinatra-1.3.3/lib/sinatra/base.rb:1389:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/thin-1.5.0/lib/thin/connection.rb:81:in `block in pre_process'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/thin-1.5.0/lib/thin/connection.rb:79:in `catch'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/thin-1.5.0/lib/thin/connection.rb:79:in `pre_process'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/eventmachine-1.0.0/lib/eventmachine.rb:1037:in `call'
  12:22:33 web.1  |   /Users/sdx/.rvm/gems/ruby-1.9.3-p327/gems/eventmachine-1.0.0/lib/eventmachine.rb:1037:in `block in spawn_threadpool'
  12:22:33 web.1  | 127.0.0.1 - - [21/Nov/2012 12:22:33] "GET /__sinatra__/500.png HTTP/1.1" 200 31056 0.0062
  </code></pre>
  
  <p>What am I doing wrong ?</p>
  
  <p><strong>UPDATED</strong> here's my mongoid.yml:</p>
  
  <pre><code>production:
      sessions:
          default:
              uri: &lt;%= ENV['MONGOLAB_URI'] %&gt;
              options:
                  skip_version_check: true
                  safe: true
  development:
      sessions:
          default:
              uri: &lt;%= ENV['MONGOLAB_URI'] %&gt;
  </code></pre>