**Impacted versions:**
* 9.0

**Steps to reproduce:**
* Enable multi currencies
* Make sure that the current rate of a foreign currency (i.e. EUR) is not 1.0 (i.e. 0.84)
* Create a purchasable product with a cost (i.e. 33$)
* Create a vendor bill in a foreign currency (i.e. EUR)
* Add the product on the invoice

**Current behavior:**
* The unit price will be 23.28 == (33 * 0.84) * 0.84

**Expected behavior:**
* The unit price should be 27,72 == 33 * 0.84
* Probably due to this line of code: https://github.com/odoo/odoo/blob/9.0/addons/account/models/account_invoice.py#L1241

**Video/Screenshot link (optional):**
* On Runbot Community 9.0: https://www.youtube.com/watch?v=60qPmczo5vk


if self._context.get('default_journal_id', False):
            return self.env['account.journal'].browse(self._context.get('default_journal_id'))
        inv_type = self._context.get('type', 'out_invoice')
        inv_types = inv_type if isinstance(inv_type, list) else [inv_type]
        company_id = self._context.get('company_id', self.env.user.company_id.id)
        domain = [
            ('type', 'in', filter(None, map(TYPE2JOURNAL.get, inv_types))),
            ('company_id', '=', company_id),
        ]
        return self.env['account.journal'].search(domain, limit=1)
    @api.model
    def _default_currency(self):
        journal = self._default_journal()
        return journal.currency_id or journal.company_id.currency_id or self.env.user.company_id.currency_id
    @api.model
    def _get_reference_type(self):