[FIX] project,sale_timesheet: default partner on billed task

addons/project/models/project.py

@@ -410,6 +410,7 @@ class Task(models.Model):
             result.update(self._subtask_values_from_parent(result['parent_id']))
         return result
 
+    @api.model
     def _get_default_partner(self):
         if 'default_project_id' in self.env.context:
             default_project_id = self.env['project.project'].browse(self.env.context['default_project_id'])
@@ -478,7 +479,7 @@ class Task(models.Model):
         index=True, track_visibility='always')
     partner_id = fields.Many2one('res.partner',
         string='Customer',
-        default=_get_default_partner)
+        default=lambda self: self._get_default_partner())
     manager_id = fields.Many2one('res.users', string='Project Manager', related='project_id.user_id', readonly=True, related_sudo=False)
     company_id = fields.Many2one('res.company',
         string='Company',

addons/sale_timesheet/models/project.py

@@ -56,11 +56,14 @@ class Project(models.Model):
 class ProjectTask(models.Model):
     _inherit = "project.task"
 
+    @api.model
     def _get_default_partner(self):
-        partner = super(ProjectTask, self)._get_default_partner()
+        partner = False
         if 'default_project_id' in self.env.context:  # partner from SO line is prior on one from project
             project = self.env['project.project'].browse(self.env.context['default_project_id'])
             partner = project.sale_line_id.order_partner_id
+        if not partner:
+            partner = super(ProjectTask, self)._get_default_partner()
         return partner
 
     @api.model