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?
""" Used to validate a batch of reconciliations in a single call
            :param data: list of dicts containing:
                - 'type': either 'partner' or 'account'
                - 'id': id of the affected res.partner or account.account
                - 'mv_line_ids': ids of exisiting account.move.line to reconcile
                - 'new_mv_line_dicts': list of dicts containing values suitable for account_move_line.create()
        """
        for datum in data:
            if len(datum['mv_line_ids']) >= 1 or len(datum['mv_line_ids']) + len(datum['new_mv_line_dicts']) >= 2:
                self.env['account.move.line'].browse(datum['mv_line_ids']).process_reconciliation(datum['new_mv_line_dicts'])
            if datum['type'] == 'partner':
                partners = self.env['res.partner'].browse(datum['id'])
                partners.mark_as_reconciled()
            if datum['type'] == 'account':
                accounts = self.env['account.account'].browse(datum['id'])
                accounts.mark_as_reconciled()
    @api.multi
    def process_reconciliation(self, new_mv_line_dicts):