What is the ruling on affirming a temporary marriage (Mut'ah) contract upon conversion to Islam?

Primary text

If they have a temporary marriage contract (Nikah Mut'ah), it shall not be affirmed. If the term has expired, no marriage remains between them. If they are still within the term, they did not believe in its permanence, whereas marriage is a perpetual contract. However, if they believed in the nullity of the condition but the validity of the marriage as perpetual, then it is affirmed.