In 11.07e724f96c5is_product_variant has been introduced back (it was removed in 10.0b747b05fa). But related of _inherits are computed on the related model so is_product_variant would always be false. Without fix, added test fails with: AssertionError: Items in the first set but not the second: True, Items in the second set but not the first: False, Product variants are variants fixes #26961 related to opw-1814973 closes #27163