pdateNonEmpty :: Repo -> [SHA] -> Queue ()
updateNonEmpty repo commits =
  update repo commits >>= liftIO . assertBool "queue was empty" . not

updateNonEmpty :: Repo -> [SHA] -> Queue ()
updateNonEmpty repo commits =
  update repo commits >>= liftIO . assertBool "queue was empty" . not
updateNonEmpty repo commits =
  update repo commits >>= liftIO . assertBool "queue was empty" . not