Bug: conflict between associating document and creating new locale

**Describe the bug**
I [translated the CPS2022 article into german](https://www.camptocamp.org/articles/history/1463470/de), which took some time working on the edit page. During that time, someone associated new photos to the article. The unexpected result was that the creation of the new locale german erased these associations, see [Association history](https://www.camptocamp.org/associations-history?offset=50&d=1463470) at 2022-09-29 16:34:28 . This should not happen.