# File lib/bundler/source/rubygems.rb, line 348
      def installed_specs
        @installed_specs ||= Index.build do |idx|
          Bundler.rubygems.all_specs.reverse_each do |spec|
            next if spec.name == "bundler"
            spec.source = self
            if Bundler.rubygems.spec_missing_extensions?(spec, false)
              Bundler.ui.debug "Source #{self} is ignoring #{spec} because it is missing extensions"
              next
            end
            idx << spec
          end
        end
      end