# File lib/bundler/source/rubygems.rb, line 333
      def remote_specs
        @remote_specs ||= Index.build do |idx|
          index_fetchers = fetchers - api_fetchers

          # gather lists from non-api sites
          index_fetchers.each do |f|
            Bundler.ui.info "Fetching source index from #{f.uri}"
            idx.use f.specs_with_retry(nil, self)
          end

          # because ensuring we have all the gems we need involves downloading
          # the gemspecs of those gems, if the non-api sites contain more than
          # about 100 gems, we just treat all sites as non-api for speed.
          allow_api = idx.size < API_REQUEST_LIMIT && dependency_names.size < API_REQUEST_LIMIT
          Bundler.ui.debug "Need to query more than #{API_REQUEST_LIMIT} gems." \
            " Downloading full index instead..." unless allow_api

          if allow_api
            api_fetchers.each do |f|
              Bundler.ui.info "Fetching gem metadata from #{f.uri}", Bundler.ui.debug?
              idx.use f.specs_with_retry(dependency_names, self)
              Bundler.ui.info "" unless Bundler.ui.debug? # new line now that the dots are over
            end

            # Suppose the gem Foo depends on the gem Bar.  Foo exists in Source A.  Bar has some versions that exist in both
            # sources A and B.  At this point, the API request will have found all the versions of Bar in source A,
            # but will not have found any versions of Bar from source B, which is a problem if the requested version
            # of Foo specifically depends on a version of Bar that is only found in source B. This ensures that for
            # each spec we found, we add all possible versions from all sources to the index.
            loop do
              idxcount = idx.size
              api_fetchers.each do |f|
                Bundler.ui.info "Fetching version metadata from #{f.uri}", Bundler.ui.debug?
                idx.use f.specs_with_retry(idx.dependency_names, self), true
                Bundler.ui.info "" unless Bundler.ui.debug? # new line now that the dots are over
              end
              break if idxcount == idx.size
            end

            if api_fetchers.any?
              # it's possible that gems from one source depend on gems from some
              # other source, so now we download gemspecs and iterate over those
              # dependencies, looking for gems we don't have info on yet.
              unmet = idx.unmet_dependency_names

              # if there are any cross-site gems we missed, get them now
              api_fetchers.each do |f|
                Bundler.ui.info "Fetching dependency metadata from #{f.uri}", Bundler.ui.debug?
                idx.use f.specs_with_retry(unmet, self)
                Bundler.ui.info "" unless Bundler.ui.debug? # new line now that the dots are over
              end if unmet.any?
            else
              allow_api = false
            end
          end

          unless allow_api
            api_fetchers.each do |f|
              Bundler.ui.info "Fetching source index from #{f.uri}"
              idx.use f.specs_with_retry(nil, self)
            end
          end
        end
      end