'Saves m2m fields.
Model instance need to have a primary key value before
a many-to-many relationship can be used.'

def save_m2m(self, obj, data, using_transactions, dry_run):

    if ((not using_transactions) and dry_run):
        pass
    else:
        for field in self.get_import_fields():
            if (not isinstance(field.widget, widgets.ManyToManyWidget)):
                continue
            self.import_field(field, obj, data)
