This commit fixes the case where portal_customer is not added in the
recipients group by the portal mixin.
Steps to reproduce:
- Go on a purchase
- Log a note and tag a user who handles notification by email
- Traceback:
```
File "/home/odoo/src/odoo/addons/purchase/models/purchase.py",
line 346, in _notify_get_recipients_groups
customer_portal_group = next(group for group in groups if group[0] == 'portal_customer')
StopIteration
```
Current Behavior:
- Traceback StopIteration
Expected Behavior:
- Log a note with the tagged (boomer) user.
See odoo/odoo@f879cf2867closesodoo/odoo#112465
X-original-commit: 7b9dd53a5573141275d41436189c782bccb96c3d
Signed-off-by: Thibault Delavallee (tde) <tde@openerp.com>