merge_db_environment_variables

# File activerecord/lib/active_record/database_configurations.rb, line 178
      def merge_db_environment_variables(current_env, configs)
        configs.map do |config|
          next config if config.url_config? || config.env_name != current_env

          url_config = environment_url_config(current_env, config.spec_name, config.config)
          url_config || config
        end
      end