code: def get_repo_and_path_fragment(self, doc_id):
          
          shard = self.get_shard(doc_id)
          return shard.name, shard.get_rel_path_fragment(doc_id)
docs: For `doc_id` returns a list of:
              [0] the repo name and,
              [1] the path from the repo to the doc file.
          This is useful because
          (if you know the remote), it lets you construct the full path.