What is the ruling if the heir of the testator has intercourse with a bequeathed female slave before acceptance, causing her to give birth?

Primary text

If the bequeathed item is a female slave and the testator's heir has intercourse with her, she becomes an Umm Walad to that heir, and her child is free, because the intercourse occurred under the heir's perceived ownership. The heir is then liable to the legatee for the price (value) of the slave upon the legatee's acceptance.