fix regression

class ServiceForm(ModelForm):

    def clean_adhesion(self):

        if self.instance.adhesion.pk != self.cleaned_data['adhesion'].pk \

        if hasattr(self.instance, 'adhesion') \

                and self.instance.adhesion.pk != self.cleaned_data['adhesion'].pk \

                and not self.instance.is_active():

            raise ValidationError('Il n’est pas possible de ré-affecter à un autre adhérent un service inactif (i.e. sans allocations actives).')

        return self.cleaned_data['adhesion']

    form = ServiceForm

    def save_model(self, request, srv, form, change):

        if 'adhesion' in form.changed_data:

        if srv.pk and 'adhesion' in form.changed_data:

            with transaction.atomic():

                old_srv = Service.objects.get(pk=srv.pk)

                adhesion = srv.adhesion