Have scholars invalidated the fast of one who partially reinserted his stool that exited from the anus?

We have not found a text on this issue, and it is inconceivable to return feces after they have exited. What is conceivable is to prevent their exit and to hold them back, and this does not invalidate the fast, because nothing has entered the body cavity. The assertion that the fast is broken by such an act is far-fetched, because it is neither eating nor drinking, nor is it in their meaning.