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?
self._update_check()
        move_ids = set()
        for line in self:
            if line.move_id.id not in move_ids:
                move_ids.add(line.move_id.id)
        result = super(AccountMoveLine, self).unlink()
        if self._context.get('check_move_validity', True) and move_ids:
            self.env['account.move'].browse(list(move_ids))._post_validate()
        return result
    @api.multi
    def write(self, vals):
        if ('account_id' in vals) and self.env['account.account'].browse(vals['account_id']).deprecated:
            raise UserError(_('You cannot use deprecated account.'))
        if any(key in vals for key in ('account_id', 'journal_id', 'date', 'move_id', 'debit', 'credit')):
            self._update_check()
        if not self._context.get('allow_amount_currency') and any(key in vals for key in ('amount_currency', 'currency_id')):
            #hac
            #thi
            self._update_check()
        #whe
        if vals.get('expected_pay_date') and self.invoice_id:
            msg = _('New expected payment date: ') + vals['expected_pay_date'] + '.\n' + vals.get('internal_note', '')
            self.invoice_id.message_post(body=msg) #TOD
        #whe
        for record in self:
            if 'statement_id' in vals and record.payment_id:
                # In