Two-way associations automatically connect product variants

[ts-mothership]

Description

It is possible to create two-way associations for products. When connecting two product models and updating a variant through the administration, something strange happens: The variant is also connected to the model as association. This goes so far that possibly all variants are connected to a model and persisted into database even though no association was changed in administration.

Version

Akeneo v7.x

Steps to reproduce

1. Create a two-way association
2. Create two product models, each with at least one variant
3. Connect both models through the two-way association
4. Switch to a product variant
5. Click on Save
6. Open the the other product model and check associations => Product model contains the variant

How it should work

If a variant is already part of the association through the model, the variant should not be added again as association.