code: async function(repo_name, library_name) {
        let library = (await this.getContribData()).libraries.find(lib => lib.repo_name === repo_name && lib.library_name === library_name);
        return library ? library.repo_tag : false;
      }
docs: Returns the tag name of the given library in the given contrib repository, if installed.
  Returns false if not installed.
  @param {String} repo_name
  @param {String} library_name
  @return {String|false}