code: async function getBranchPr(branchName, refreshCache) {
    logger.debug(`getBranchPr(${branchName})`);
    const existingPr = await findPr(branchName, null, 'open');
    return existingPr ? getPr(existingPr.number, refreshCache) : null;
  }
docs: Returns the Pull Request for a branch. Null if not exists.