When creating a timesheet, several fields need to be recomputed:
- `currency_id`
- `group_id`
- `department_id`
- `is_timesheet`
- `validated`
When `validated` is computed before the other fields, the recomputation
will lead to an `AccessError` because of the rule
`hr_timesheet.timesheet_line_rule_user`.
Since the test `test_timesheet_validation_user` expects an
`AccessError`, the test succeeds. However, from time to time,
`validated` is computed last => the `AccessError` is not raised.
Actually, a `ValidationError` should be raised in this case (from the
`create` override in `timesheet_grid`).