[If] a non-Jew gave [ingredients] to a Jew to make a dough for him, [it is] exempt from challah. [If] he gave it to him as a gift, [if] before he had thoroughly mixed [it], it is obligated [in challah]; but [if] after he had thoroughly mixed it, it is exempt.  [If] one makes a dough [together] with a non-Jew, if [the portion] of the Jew does not consist of the minimum measure for challah [liability], it is exempt from challah.