title: Deactivate a Gem - "you have already activated rake 0.9.3.beta.1, but my Gemfile requires rake 0.9.2"
body: <p>I'm trying to run a migration but I keep getting the error message that is:</p>
  
  <pre><code>rake aborted! Undefined method prerequisite for nil:NilClass.
  </code></pre>
  
  <p>It seems that somehow I activated a gem called <code>rake 0.9.3.beta.1</code> - however I have since changed the gem <code>bundle install</code> and run <code>bundle show</code> rake and it shows that <code>rake 0.9.2</code> is installed.  I'm using Git for the first time so I thought that maybe it had something to do with the application still using the beta version of rake - but I've done a push and it shows that the gemfile has been updated.</p>
  
  <p>and when I look down into the gem libraries I can only see the <code>rake 0.9.2</code> version.  Where should I be looking?</p>
  
  <p>I also have a Rails:Railtie deprecated warning - but I'm thinking that this doesn't have anything to do with my migration problems.  Its telling me to use config.app_generators in config/application.rb instead of Railtie - but i can't see that in the file. </p>
  
  <p>This is the Config/application.rb file </p>
  
  <pre><code>require File.expand_path('../boot', __FILE__)
  
  # Pick the frameworks you want:
   require "active_record/railtie"
  require "action_controller/railtie"
  require "action_mailer/railtie"
  require "active_resource/railtie"
   require "sprockets/railtie"
  Bundler.require *Rails.groups(:assets) if defined?(Bundler)
  
  module CrowdshareApp
    class Application &lt; Rails::Application
    config.encoding = "utf-8"
  config.filter_parameters += [:password]
  config.assets.enabled = true
    end
  end
  </code></pre>
  
  <p>My Gemfile looks like this:</p>
  
  <pre><code>source 'http://rubygems.org'
  
  gem 'rails', '3.1.0.rc5'
  gem 'sqlite3' 
  group :assets do
    gem 'sass-rails', "~&gt; 3.1.0.rc"
    gem 'coffee-rails', "~&gt; 3.1.0.rc"
    gem 'uglifier'
  end
  
  gem 'jquery-rails'
  group :development do
    gem   'rspec-rails', '2.0.0.beta.18'
  end
  
  group :test do
    gem 'rspec', '2.0.0.beta.18'
  end
  </code></pre>
  
  <p>and the Gemfile.lock file has the following:</p>
  
  <pre><code>GEM
    remote: http://rubygems.org/
    specs:
      actionmailer (3.1.0.rc5)
        actionpack (= 3.1.0.rc5)
        mail (~&gt; 2.3.0)
      actionpack (3.1.0.rc5)
        activemodel (= 3.1.0.rc5)
        activesupport (= 3.1.0.rc5)
        builder (~&gt; 3.0.0)
        erubis (~&gt; 2.7.0)
        i18n (~&gt; 0.6)
        rack (~&gt; 1.3.1)
        rack-cache (~&gt; 1.0.2)
        rack-mount (~&gt; 0.8.1)
        rack-test (~&gt; 0.6.0)
        sprockets (~&gt; 2.0.0.beta.12)
      activemodel (3.1.0.rc5)
        activesupport (= 3.1.0.rc5)
        bcrypt-ruby (~&gt; 2.1.4)
        builder (~&gt; 3.0.0)
        i18n (~&gt; 0.6)
      activerecord (3.1.0.rc5)
        activemodel (= 3.1.0.rc5)
        activesupport (= 3.1.0.rc5)
        arel (~&gt; 2.1.4)
        tzinfo (~&gt; 0.3.29)
      activeresource (3.1.0.rc5)
        activemodel (= 3.1.0.rc5)
        activesupport (= 3.1.0.rc5)
      activesupport (3.1.0.rc5)
        multi_json (~&gt; 1.0)
      arel (2.1.4)
      bcrypt-ruby (2.1.4-x86-mingw32)
      builder (3.0.0)
      coffee-rails (3.1.0.rc.5)
        actionpack (~&gt; 3.1.0.rc1)
        coffee-script (&gt;= 2.2.0)
        railties (~&gt; 3.1.0.rc1)
        sprockets (&gt;= 2.0.0.beta.9)
      coffee-script (2.2.0)
        coffee-script-source
        execjs
      coffee-script-source (1.1.2)
      diff-lcs (1.1.2)
      erubis (2.7.0)
      execjs (1.2.4)
        multi_json (~&gt; 1.0)
      hike (1.2.0)
      i18n (0.6.0)
      jquery-rails (1.0.13)
        railties (~&gt; 3.0)
        thor (~&gt; 0.14)
      mail (2.3.0)
        i18n (&gt;= 0.4.0)
        mime-types (~&gt; 1.16)
        treetop (~&gt; 1.4.8)
      mime-types (1.16)
      multi_json (1.0.3)
      nokogiri (1.5.0-x86-mingw32)
      polyglot (0.3.2)
      rack (1.3.2)
      rack-cache (1.0.2)
        rack (&gt;= 0.4)
      rack-mount (0.8.2)
        rack (&gt;= 1.0.0)
      rack-ssl (1.3.2)
        rack
      rack-test (0.6.1)
        rack (&gt;= 1.0)
      rails (3.1.0.rc5)
        actionmailer (= 3.1.0.rc5)
        actionpack (= 3.1.0.rc5)
        activerecord (= 3.1.0.rc5)
        activeresource (= 3.1.0.rc5)
        activesupport (= 3.1.0.rc5)
        bundler (~&gt; 1.0)
        railties (= 3.1.0.rc5)
      railties (3.1.0.rc5)
        actionpack (= 3.1.0.rc5)
        activesupport (= 3.1.0.rc5)
        rack-ssl (~&gt; 1.3.2)
        rake (&gt;= 0.8.7)
        rdoc (~&gt; 3.4)
        thor (~&gt; 0.14.6)
      rake (0.9.2)
      rdoc (3.9.2)
      rspec (2.0.0.beta.18)
        rspec-core (= 2.0.0.beta.18)
        rspec-expectations (= 2.0.0.beta.18)
        rspec-mocks (= 2.0.0.beta.18)
      rspec-core (2.0.0.beta.18)
      rspec-expectations (2.0.0.beta.18)
        diff-lcs (&gt;= 1.1.2)
      rspec-mocks (2.0.0.beta.18)
      rspec-rails (2.0.0.beta.18)
        rspec (&gt;= 2.0.0.beta.14)
        webrat (&gt;= 0.7.0)
      sass (3.1.7)
      sass-rails (3.1.0.rc.5)
        actionpack (~&gt; 3.1.0.rc1)
        railties (~&gt; 3.1.0.rc1)
        sass (&gt;= 3.1.4)
        sprockets (&gt;= 2.0.0.beta.9)
      sprockets (2.0.0.beta.13)
        hike (~&gt; 1.2)
        rack (~&gt; 1.0)
        tilt (!= 1.3.0, ~&gt; 1.1)
      sqlite3 (1.3.4-x86-mingw32)
      thor (0.14.6)
      tilt (1.3.2)
      treetop (1.4.10)
        polyglot
        polyglot (&gt;= 0.3.1)
      tzinfo (0.3.29)
      uglifier (1.0.0)
        execjs (&gt;= 0.3.0)
        multi_json (&gt;= 1.0.2)
      webrat (0.7.3)
        nokogiri (&gt;= 1.2.0)
        rack (&gt;= 1.0)
        rack-test (&gt;= 0.5.3)
  
  PLATFORMS
    x86-mingw32
  
  DEPENDENCIES
    coffee-rails (~&gt; 3.1.0.rc)
    jquery-rails
    rails (= 3.1.0.rc5)
    rspec (= 2.0.0.beta.18)
    rspec-rails (= 2.0.0.beta.18)
    sass-rails (~&gt; 3.1.0.rc)
    sqlite3
    uglifier
  </code></pre>