What is the ruling on an abandoned infant found in a conquered territory of Dar al-Islam, such as the cities of Sham (Levant)?

Primary text

If a Muslim resides in a conquered territory of Dar al-Islam, the abandoned infant found there is ruled to be a Muslim, as it is presumed the infant belongs to that Muslim, favoring Islam. However, if no Muslim resides there and all inhabitants are people of protection (Ahl al-Dhimma), the infant is ruled to be a disbeliever, because the presumption favoring Islam requires a possibility of Muslim presence. This detailed differentiation is attributed to the Shafi'i school.