[FIX] account: unreconcile cash basis

- Set up a tax as 'Based on Payment'
- Create an invoice at date D with this tax
- Pay the invoice at date D+1
- Unreconcile

A reversal entry is made at the current date, while it should be at the
payment date D+1.

We make sure to use the payment date only if the payment period has not
been locked.

Fixes #25738
opw-1870467

addons/account/models/account_move.py

@@ -1884,8 +1884,11 @@ class AccountPartialReconcile(models.Model):
             if rec.full_reconcile_id:
                 full_to_unlink |= rec.full_reconcile_id
         #reverse the tax basis move created at the reconciliation time
-        move = self.env['account.move'].search([('tax_cash_basis_rec_id', 'in', self._ids)])
-        move.reverse_moves()
+        for move in self.env['account.move'].search([('tax_cash_basis_rec_id', 'in', self._ids)]):
+            if move.date > (move.company_id.period_lock_date or '0000-00-00'):
+                move.reverse_moves(date=move.date)
+            else:
+                move.reverse_moves()
         res = super(AccountPartialReconcile, self).unlink()
         if full_to_unlink:
             full_to_unlink.unlink()