Impacted versions:
At least version 10, version 11(Can only re-produce the problem sometimes)

Steps to reproduce:
Please see this screencast recorded on odoo runbot.
https://youtu.be/cSPQvp9jQJc

Current behavior:
When users search by account in Journal Entries List View. A special value "dummy_account_id" is set in context, in order to facilitate search by account on account.move level.
With this context value , when users create a journal entries, the system will add default value before the creation.

https://github.com/odoo/odoo/blob/fc69b37cf710623ea215cd085e998679d8c50985/odoo/models.py#L3802

This method will set "dummy_account_id" to the previously searched account in vals.

Then the system continue creating account.move and related account.move.line records.
It is fine until the system run this:
https://github.com/odoo/odoo/blob/fc69b37cf710623ea215cd085e998679d8c50985/odoo/models.py#L3830

Since "dummy_account_id" is related field, and it now has value. The system will change the first related  account.move.line record to dummy_account_id.

Eventualy, the account is wrongly set to "dummy_account_id".

Expected behavior:
This is a feature which will fill the form field value with searched value for users. But the journal entry creation should not be affected by dummy_account_id, since it is only for searching purpose.

@Yenthe666 Would you please review this issue and help to bring related odoo staff to this issue?
""" Automatically create a journal entry to book the exchange rate difference.
            That new journal entry is made in the company `currency_exchange_journal_id` and one of its journal
            items is matched with the other lines to balance the full reconciliation.
        """
        for rec in self:
            if not rec.company_id.currency_exchange_journal_id:
                raise UserError(_("You should configure the 'Exchange Rate Journal' in the accounting settings, to manage automatically the booking of accounting entries related to differences between exchange rates."))
            if not rec.company_id.income_currency_exchange_account_id.id:
                raise UserError(_("You should configure the 'Gain Exchange Rate Account' in the accounting settings, to manage automatically the booking of accounting entries related to differences between exchange rates."))
            if not rec.company_id.expense_currency_exchange_account_id.id:
                raise UserError(_("You should configure the 'Loss Exchange Rate Account' in the accounting settings, to manage automatically the booking of accounting entries related to differences between exchange rates."))
            move_vals = {'journal_id': rec.company_id.currency_exchange_journal_id.id}
            # Th
            # of 
            # re
            if move_date > rec.company_id.fiscalyear_lock_date:
                move_vals['date'] = move_date
            move = rec.env['account.move'].create(move_vals)
            amount_diff = rec.company_id.currency_id.round(amount_diff)
            diff_in_currency = currency.round(diff_in_currency)
            line_to_reconcile = rec.env['account.move.line'].with_context(check_move_validity=False).create({
                'name': _('Currency exchange rate difference'),