In a multicompany scenario where a contact belongs to a company and has contracts in several companies, if the user goes to the contact to edit anything, when saving, it will trigger the recomputation of the `commercial_partner_id` field, which gets populated to all the related contracts, and will undeniably fail with an `AccessError`.
A simple test is provided that, without the fix, fails like this:
```
2020-06-25 07:21:24,859 33 ERROR devel odoo.addons.contract.tests.test_contract: ERROR: test_multicompany_partner_edited (odoo.addons.contract.tests.test_contract.TestContract)
2020-06-25 07:21:24,859 33 ERROR devel odoo.addons.contract.tests.test_contract: ` Editing a partner with contracts in several companies works.
2020-06-25 07:21:24,859 33 ERROR devel odoo.addons.contract.tests.test_contract: Traceback (most recent call last):
2020-06-25 07:21:24,859 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/auto/addons/contract/tests/test_contract.py", line 2513, in test_multicompany_partner_edited
2020-06-25 07:21:24,859 33 ERROR devel odoo.addons.contract.tests.test_contract: ` 'parent_id': parent_partner.id,
2020-06-25 07:21:24,859 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/auto/addons/partner_autocomplete/models/res_partner.py", line 183, in write
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` res = super(ResPartner, self).write(values)
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/custom/src/odoo/odoo/addons/base/models/res_partner.py", line 570, in write
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` result = result and super(Partner, self).write(vals)
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/auto/addons/mail/models/mail_thread.py", line 321, in write
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` result = super(MailThread, self).write(values)
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/auto/addons/mail/models/mail_activity.py", line 613, in write
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` return super(MailActivityMixin, self).write(vals)
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/custom/src/odoo/odoo/models.py", line 3381, in write
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` self.recompute()
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/custom/src/odoo/odoo/models.py", line 5308, in recompute
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` target._write(dict(vals))
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/custom/src/odoo/odoo/models.py", line 3433, in _write
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` self.check_access_rule('write')
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` File "/opt/odoo/custom/src/odoo/odoo/models.py", line 3081, in check_access_rule
2020-06-25 07:21:24,860 33 ERROR devel odoo.addons.contract.tests.test_contract: ` + ' - ({} {}, {} {})'.format(_('Records:'), invalid.ids[:6], _('User:'), self._uid)
2020-06-25 07:21:24,861 33 ERROR devel odoo.addons.contract.tests.test_contract: ` odoo.exceptions.AccessError: ('The requested operation cannot be completed due to security restrictions. Please contact your system administrator.\n\n(Document type: Contract, Operation: write) - (Records: [101], User: 12)', None)
```
@Tecnativa TT24482
Done through an extra field + inverse in the existing compute. This way, we have
the flexibility of auto-remove custom value if it matches the computed one + we don't
need extra changes in the rest of the code.
Previous related field was not accurated nor editable. Now the field is got
properly from a computed field.
Reviewing this, as the currency was taken (and it continues being taken) from the partner
pricelist if no pricelist is explicitly set, automatic price should use the same logic for
using partner pricelist.
