func (w *worker) putFile(c *client.APIClient) error {
	if len(w.started) == 0 {
		return nil
	}
	commit := w.started[w.rand.Intn(len(w.started))]
	if _, err := c.PutFile(commit.Repo.Name, commit.ID, w.randString(10), w.reader()); err != nil {
		return err
	}
	return nil
}
func (w *worker) putFile(c *client.APIClient) error {
	if len(w.started) == 0 {
		return nil
	}
	commit := w.started[w.rand.Intn(len(w.started))]
	if _, err := c.PutFile(commit.Repo.Name, commit.ID, w.randString(10), w.reader()); err != nil {
		return err
	}
	return nil
}
// putFile puts a file with random contents into a random open commit (or exits
// early if there are none)