title: rails s : undefined method `symbolize_keys'
body: <p>I have a rails 3.2.12 app, but when I ran <code>rails s</code>, I got the following error : <code>connection_specification.rb:45:in 'resolve_hash_connection': undefined method 'symbolize_keys' for #&lt;String:0x00000006c16b40&gt; (NoMethodError)</code></p>
  
  <p>the connection_specification.rb concerned method :</p>
  
  <pre><code>def resolve_hash_connection(spec) # :nodoc:
    spec = spec.symbolize_keys # Line 45
  
    raise(AdapterNotSpecified, "database configuration does not specify adapter") unless spec.key?(:adapter)
  
    begin
      require "active_record/connection_adapters/#{spec[:adapter]}_adapter"
    rescue LoadError =&gt; e
      raise LoadError, "Please install the #{spec[:adapter]} adapter: `gem install activerecord-#{spec[:adapter]}-adapter` (#{e.message})", e.backtrace
    end
  
    adapter_method = "#{spec[:adapter]}_connection"
  
    ConnectionSpecification.new(spec, adapter_method)
  end
  </code></pre>