Fail to update a user's role on a project

On nG6 (prod), the user 513 was both member and admin on a project.

We should check if another user is concerned, and find why there were 2 rows in 'fe_rights' linking the user to the project.

Kanboard link : https://genomique.genotoul.fr/kanboard/?controller=TaskViewController&action=show&project_id=18&task_id=1132