title: Could not find ffi in any of the sources
body: <p>On OS X 10.9.5...</p>
  
  <p><strong>Gemfile</strong></p>
  
  <pre><code>source 'https://rubygems.org'
  
  gem 'rails', '4.2.0'
  gem 'sass-rails', '5.0.4'
  gem 'uglifier', '2.7.2'
  gem 'coffee-rails', '4.1.0'
  gem 'jquery-rails', '4.0.5'
  gem 'turbolinks', '2.5.3'
  gem 'jbuilder', '2.3.1'
  gem 'sdoc', '0.4.1', group: :doc
  gem 'mongoid', '4.0.2'
  gem 'mongoid-grid_fs', '2.1.0'
  gem 'watir-rails', '1.1.0'
  
  group :development, :test do
    gem 'byebug', '6.0.2'
    gem 'web-console', '2.2.1'
    gem 'spring', '1.3.6'
  end
  </code></pre>
  
  <p><strong>Terminal</strong></p>
  
  <pre><code>$ bundle install
  ...
  Installing ffi 1.9.10 with native extensions
  ...
  Bundle complete! 14 Gemfile dependencies, 68 gems now installed.
  Use `bundle show [gemname]` to see where a bundled gem is installed.
  $ bundle show ffi
  /Users/me/.rvm/gems/ruby-2.2.2/gems/ffi-1.9.10
  $ rails c
  Could not find ffi-1.9.10 in any of the sources
  Run `bundle install` to install missing gems
  </code></pre>
  
  <p>I tried placing "gem 'ffi', '1.9.10'" in my Gemfile.</p>
  
  <p>I tried removing my Gemfile.lock and repeating this process.</p>
  
  <p>I tried <code>bundle exec rails c</code>.</p>
  
  <p>I tried <code>gem install ffi --version 1.0.11</code>, which seems to be the dependency for childprocess-0.5.6.</p>
  
  <p>None of these attempts make any difference. Any ideas?</p>