[FIX] (project_)pad: Don't create/copy pads on tasks that don't use them

Purpose
=======

Currently if a project doesn't use pads, the created and duplicated tasks will initialize/copy them. That could be a real issue when migrating customers if we create a task for all the existing issues, since the models have been merged.

Specification
=============

Avoid this falsy behavior. We're forced to crappy fix with a context key as the project.task model 'inherit' from pad.common.

addons/pad/models/pad.py

@@ -106,6 +106,8 @@ class PadCommon(models.AbstractModel):
 
         # In case the pad is created programmatically, the content is not filled in yet since it is
         # normally initialized by the JS layer
+        if self.env.context.get('pad_no_create', False):
+            return pad
         for k, field in self._fields.items():
             if hasattr(field, 'pad_content_field') and k not in vals:
                 ctx = {
@@ -141,6 +143,9 @@ class PadCommon(models.AbstractModel):
             default = {}
         for k, field in self._fields.items():
             if hasattr(field, 'pad_content_field'):
-                pad = self.pad_generate_url()
-                default[k] = pad.get('url')
+                if self.env.context.get('pad_no_create', False):
+                    default[k] = ''
+                else:
+                    pad = self.pad_generate_url()
+                    default[k] = pad.get('url')
         return super(PadCommon, self).copy(default)

addons/pad_project/models/project.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 # Part of Odoo. See LICENSE file for full copyright and licensing details.
 
-from odoo import fields, models
+from odoo import api, fields, models
 
 
 class ProjectTask(models.Model):
@@ -11,6 +11,20 @@ class ProjectTask(models.Model):
     description_pad = fields.Char('Pad URL', pad_content_field='description')
     use_pad = fields.Boolean(related="project_id.use_pads", string="Use collaborative pad")
 
+    @api.model
+    def create(self, vals):
+        # When using quick create, the project_id is in the context, not in the vals
+        project_id = vals.get('project_id', False) or self.default_get(['project_id'])['project_id']
+        if not self.env['project.project'].browse(project_id).use_pads:
+            self = self.with_context(pad_no_create=True)
+        return super(ProjectTask, self).create(vals)
+
+    @api.multi
+    def copy(self, default=None):
+        if not self.use_pad:
+            self = self.with_context(pad_no_create=True)
+        return super(ProjectTask, self).copy(default)
+
 
 class ProjectProject(models.Model):
     _inherit = "project.project"