[FIX] website: website-specific child views

On a eCommerce page were there was no SEO optimization change:
- Customize > Activate "eCommerce categories"
- Customize > Activate "Colapsible category list"
- Promote > Optimize SEO > Change description > Save

Nothing happens.

Actually, an SQL error is raised because of the `ondelete='restrict'`
set at:

https://github.com/odoo/odoo/blob/897feb553e6ef75af9434cb77436b26abde3a761/odoo/addons/base/models/ir_ui_view.py#L212

In this case, we have the following structure:

```
View 1
|
---> View 2 (Website-specific)
|
---> View 3 (Website-specific)
```

For example:

```
Products
|
---> eCommerce Categories (Website-specific)
|
---> Collapsible Category List (Website-specific)
```

Since the inherited view (View 2) is website-specific, we duplicate it
and try to unlink it. However, this view has children, which raises the
error.

To solve the issue, we re-attach the children of the inherited view to
its copy. In a realistic situation, the children of a website-specific
view should also be website-specific, so there is no need to apply the
'copy or re-attach' logic recursively.

We end up with:

```
View 1 (Website-specific, duplicated)
|
---> View 2 (Website-specific, duplicated)
|
---> View 3 (Website-specific)
```

opw-1997946

closes odoo/odoo#33787

Signed-off-by: Nicolas Martinelli (nim) <nim@odoo.com>

addons/website/models/ir_ui_view.py

@@ -83,7 +83,8 @@ class View(models.Model):
                     # original tree. Indeed, the order of children 'id' fields
                     # must remain the same so that the inheritance is applied
                     # in the same order in the copied tree.
-                    inherit_child.copy({'inherit_id': website_specific_view.id, 'key': inherit_child.key})
+                    child = inherit_child.copy({'inherit_id': website_specific_view.id, 'key': inherit_child.key})
+                    inherit_child.inherit_children_ids.write({'inherit_id': child.id})
                     inherit_child.unlink()
                 else:
                     # Trigger COW on inheriting views

addons/website/tests/test_views.py

@@ -797,6 +797,54 @@ class TestCowViewSaving(common.TransactionCase):
         all_title_updated = specific_view.website_meta_title == self.base_view.website_meta_title == "A bug got fixed by updating this field"
         self.assertEqual(all_title_updated, True, "Update on top level generic views should also be applied on specific views")
 
+    def test_multiple_inherit_level(self):
+        """ Test multi-level inheritance:
+            Base
+            |
+            ---> Extension (Website-specific)
+                |
+                ---> Extension 2 (Website-specific)
+        """
+        View = self.env['ir.ui.view']
+
+        self.inherit_view.website_id = 1
+        inherit_view_2 = View.create({
+            'name': 'Extension 2',
+            'mode': 'extension',
+            'inherit_id': self.inherit_view.id,
+            'arch': '<div position="inside">, extended content 2</div>',
+            'key': 'website.extension_view_2',
+            'website_id': 1,
+        })
+
+        total_views = View.search_count([])
+
+        # id | name        | content               | website_id | inherit  | key
+        # --------------------------------------------------------------------------------------------
+        # 1  | Base        |  base content         |     /      |     /    |  website.base_view
+        # 2  | Extension   |  , extended content   |     1      |     1    |  website.extension_view
+        # 3  | Extension 2 |  , extended content 2 |     1      |     2    |  website.extension_view_2
+
+        self.base_view.with_context(website_id=1).write({'arch': '<div>modified content</div>'})
+
+        # 2 views are created, one is deleted
+        self.assertEqual(View.search_count([]), total_views + 1)
+        self.assertFalse(self.inherit_view.exists())
+        self.assertTrue(inherit_view_2.exists())
+
+        # Verify the inheritance
+        base_specific = View.search([('key', '=', self.base_view.key), ('website_id', '=', 1)]).with_context(load_all_views=True)
+        extend_specific = View.search([('key', '=', 'website.extension_view'), ('website_id', '=', 1)])
+        self.assertEqual(extend_specific.inherit_id, base_specific)
+        self.assertEqual(inherit_view_2.inherit_id, extend_specific)
+
+        # id | name        | content               | website_id | inherit  | key
+        # --------------------------------------------------------------------------------------------
+        # 1  | Base        |  base content         |     /      |     /    |  website.base_view
+        # 4  | Base        |  modified content     |     1      |     /    |  website.base_view
+        # 5  | Extension   |  , extended content   |     1      |     4    |  website.extension_view
+        # 3  | Extension 2 |  , extended content 2 |     1      |     5    |  website.extension_view_2
+
 
 class Crawler(HttpCase):
     def setUp(self):