Remove positivity constraint in apply_voucher

src/tests/presale/test_cart.py

@@ -1827,6 +1827,7 @@ class CartTest(CartTestMixin, TestCase):
             assert cp2.voucher == v2
             assert cp2.price == Decimal('150.00')
 
+    """
     def test_voucher_apply_only_positive(self):
         with scopes_disabled():
             cp1 = CartPosition.objects.create(
@@ -1849,6 +1850,7 @@ class CartTest(CartTestMixin, TestCase):
             cp2.refresh_from_db()
             assert cp1.voucher is None
             assert cp2.voucher is None
+    """
 
     def test_voucher_apply_expired(self):
         with scopes_disabled():