findUnfinishedReleases = releaseType => {
  const unfinishedReleases = execTrim('git branch -l')
    .split('\n')
    .filter(branchName => new RegExp(`${releaseType}/.+`).test(branchName))

  if (!unfinishedReleases.length) {
    console.log(`There are no unfinished ${releasePlural(releaseType)}`)
    process.exit(0)
  }

  return unfinishedReleases.map(String.trim)
}
Find existing, unfinished release branches
@param  {String} releaseType hotfix or release
@return {Array} Array of potential unfinished branches