Steps to reproduce the bug: - Create a company C with currency = USD - Create a vendor V with a supplier currency = EUR - Create a PO for V with one line, the default currency is EUR - Save Bug: The currency of the PO was USD when saving because the field currency is in readonly when the state is draft. opw:2035640 closes odoo/odoo#35144 Signed-off-by: Simon Goffin (sig) <sig@openerp.com>