tryManifest(dir, registry, isRoot) {
    var _this6 = this;

    return (0, (_asyncToGenerator2 || _load_asyncToGenerator()).default)(function* () {
      const filename = (_index2 || _load_index2()).registries[registry].filename;

      const loc = path.join(dir, filename);
      if (yield (_fs || _load_fs()).exists(loc)) {
        const data = yield _this6.readJson(loc);
        data._registry = registry;
        data._loc = loc;
        return (0, (_index || _load_index()).default)(data, dir, _this6, isRoot);
      } else {
        return null;
      }
    })();
  }
Try and find package info with the input directory and registry.