I passed this message as feature request to developers. Thanks' for your interest in this case. I assume, right now you can create such file manually and configure it as you wish. But in this case it should be rewritten each time after publication is done.
Nearest update is 4.2.2 and it should be relesed very soon, within this or next week. But it is not possible to include 'support robots.txt' feature into this update, so probably it will be added later. Can not say for sure exact version and dates.