[FIX] test_website: upgrading inside a test is really not a good idea

Because: (1) the upgrade starts by committing the current cursor; then
(2) the upgrade instanciates a new registry to use for the database; and
(3) the test cleanup involves setting up the old registry, which creates
a new environment referring to the new registry!

The points (2) and (3) makes the field setup crash when it relies on
data stored on the registry itself: the field in the old registry tries
to set up with data stored on the old registry.

closes odoo/odoo#48920

X-original-commit: f5e5aba9e203b42b661cc3b503fd37051ec20f93
Signed-off-by: Raphael Collet (rco) <rco@openerp.com>

addons/test_website/tests/test_views_during_module_operation.py

@@ -62,6 +62,12 @@ class TestViewsDuringModuleOperation(TransactionCase):
         self.assertTrue(self.env.ref(update_module_view_to_be_t_called.key))
         self.assertTrue(self.env.ref(update_module_base_view.key))
 
+        # the upgrade of the module below instanciates a NEW registry, so we
+        # have to restore the old one in order to perform the cleanups
+        @self.addCleanup
+        def cleanup():
+            self.registry.registries[self.registry.db_name] = self.registry
+
         # Update the module
         test_website_module = self.env['ir.module.module'].search([('name', '=', 'test_website')])
         test_website_module.button_immediate_upgrade()