פירוש על עבודה זרה 130:2

The Talmud raises a difficulty—doesn’t R. Aha’s father want the water-skins to be preserved. If they burst, then he will have to give them the jugs. Thus in a sense he is invested in the preservation of the wine.

Aha’s father made a condition with the non-Jews—he would keep the jugs even if the wine-skins split and the wine was lost. In other words, he was paid up front.

It might also be a case where the non-Jews brought barrels with him to hold the wine if the wine-skins should break.