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?
if not company.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 company.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 company.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."))
        res = {'journal_id': company.currency_exchange_journal_id.id}
        # Th
        # (i
        # mo
        if move_date > company.fiscalyear_lock_date:
            res['date'] = move_date
        return res