set_key

# File lib/bundler/settings.rb, line 358
    def set_key(raw_key, value, hash, file)
      raw_key = raw_key.to_s
      value = array_to_s(value) if is_array(raw_key)

      key = key_for(raw_key)

      return if hash[key] == value

      hash[key] = value
      hash.delete(key) if value.nil?

      Validator.validate!(raw_key, converted_value(value, raw_key), hash)

      return unless file
      SharedHelpers.filesystem_access(file) do |p|
        FileUtils.mkdir_p(p.dirname)
        require "bundler/yaml_serializer"
        p.open("w") {|f| f.write(YAMLSerializer.dump(hash)) }
      end
    end