Fix bad assignment of $row

[k4emic]

This pull fixes an issue where the attribute_set_id would be assigned in the $values[$index][...], but not in the $row variable (which is pulled from $values[$index]).

I stumbled on this problem while running unittests from groupscatalog2 https://github.com/Vinai/groupscatalog2 (catalog_product entities in the global.yml file).

[k4emic]

This might not be THE way to go around it, but it solved the SQL exception that was raised because the attribute_set_id was set to 0, since this is the DEFAULT value in the catalog_product_entity table.

[robbieaverill]

Makes sense, +1