title: rails 4: mapping values are not allowed in this context at line 2 column 11 (Psych::SyntaxError)?
body: <p>I have successfully installed rails 4 and created project using rails 4.0.0</p>
  
  <pre><code>rails s
  </code></pre>
  
  <p>for the first time was working fine. But after adding 'devise' gem in gemfile</p>
  
  <pre><code> gem 'devise', '~&gt; 3.0.0.rc'
  </code></pre>
  
  <p>and running bundle install, I am getting following error. What is the cause of this error and what will be the solution for it?</p>
  
  <p>I have tried with commenting gem 'devise' section also, but now i am getting same error for every rails command.</p>
  
  <pre><code>/home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:205:in `parse':   (&lt;unknown&gt;): mapping values are not allowed in this context at line 2 column 11 (Psych::SyntaxError)
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:205:in `parse_stream'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:153:in `parse'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:129:in `load'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rubygems/config_file.rb:318:in `load_file'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rubygems/config_file.rb:191:in `initialize'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rubygems/gem_runner.rb:66:in `new'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rubygems/gem_runner.rb:66:in `do_configuration'
  from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/rubygems/gem_runner.rb:46:in `run'
  </code></pre>
  
  <p>database.yml file</p>
  
  <pre><code>development:
  adapter: mysql2
  encoding: utf8
  database: realstate_development
  pool: 5
  username: root
  password: root
  socket: /var/run/mysqld/mysqld.sock
  </code></pre>
  
  <p>gem 'devise' with any version, is showing following error on bundle, if I remove devise gem it works fine, I used rails 3.2.13 but I never faced such problem, what a strange.</p>
  
  <pre><code>Fetching gem metadata from https://rubygems.org/.........
  Fetching gem metadata from https://rubygems.org/..
  Unfortunately, a fatal error has occurred. Please see the Bundler troubleshooting documentation at http://bit.ly/bundler-issues. Thanks!
  /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:205:in `parse': (&lt;unknown&gt;): mapping values are not allowed in this context at line 2 column 11 (Psych::SyntaxError)
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:205:in `parse_stream'
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:153:in `parse'
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/2.0.0/psych.rb:129:in `load'
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/config_file.rb:318:in `load_file'
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems/config_file.rb:191:in `initialize'
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems.rb:319:in `new'
      from /home/siv/.rvm/rubies/ruby-2.0.0-p247/lib/ruby/site_ruby/2.0.0/rubygems.rb:319:in `configuration'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/rubygems_integration.rb:34:in `configuration'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/rubygems_integration.rb:53:in `sources='
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/source/rubygems.rb:250:in `remote_specs'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/source/rubygems.rb:163:in `fetch_specs'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/source/rubygems.rb:67:in `specs'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:192:in `block (2 levels) in index'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:189:in `each'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:189:in `block in index'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/index.rb:9:in `build'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:185:in `index'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:179:in `resolve'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:114:in `specs'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/definition.rb:109:in `resolve_remotely!'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/installer.rb:83:in `run'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/installer.rb:14:in `install'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/cli.rb:247:in `install'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/vendor/thor/task.rb:27:in `run'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/vendor/thor/invocation.rb:120:in `invoke_task'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/vendor/thor.rb:344:in `dispatch'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/vendor/thor/base.rb:434:in `start'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/bin/bundle:20:in `block in &lt;top (required)&gt;'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/lib/bundler/friendly_errors.rb:3:in `with_friendly_errors'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/gems/bundler-1.3.5/bin/bundle:20:in `&lt;top (required)&gt;'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/bin/bundle:23:in `load'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247@global/bin/bundle:23:in `&lt;main&gt;'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247/bin/ruby_noexec_wrapper:14:in `eval'
      from /home/siv/.rvm/gems/ruby-2.0.0-p247/bin/ruby_noexec_wrapper:14:in `&lt;main&gt;'
  </code></pre>