[FIX] core: do not register classes when _module is falsy

The goal is to avoid a class from being added in the dictionary
`MetaModel.module_to_models`.

We use this feature in tests to prevent classes extending models from
triggering bugs when reloading the registry (for whatever reason).

X-original-commit: 12db61b787b2035bf0c1f2a68a24449d484744c8

odoo/addons/test_new_api/tests/test_new_fields.py

@@ -2615,6 +2615,7 @@ class TestSelectionOndeleteAdvanced(common.TransactionCase):
 
     def test_ondelete_unexisting_policy(self):
         class Foo(models.Model):
+            _module = None
             _inherit = self.MODEL_REQUIRED
 
             my_selection = fields.Selection(selection_add=[
@@ -2628,6 +2629,7 @@ class TestSelectionOndeleteAdvanced(common.TransactionCase):
 
     def test_ondelete_default_no_default(self):
         class Foo(models.Model):
+            _module = None
             _inherit = self.MODEL_BASE
 
             my_selection = fields.Selection(selection_add=[
@@ -2641,6 +2643,7 @@ class TestSelectionOndeleteAdvanced(common.TransactionCase):
 
     def test_ondelete_required_null_explicit(self):
         class Foo(models.Model):
+            _module = None
             _inherit = self.MODEL_REQUIRED
 
             my_selection = fields.Selection(selection_add=[
@@ -2654,6 +2657,7 @@ class TestSelectionOndeleteAdvanced(common.TransactionCase):
 
     def test_ondelete_required_null_implicit(self):
         class Foo(models.Model):
+            _module = None
             _inherit = self.MODEL_REQUIRED
 
             my_selection = fields.Selection(selection_add=[

odoo/models.py

@@ -161,7 +161,7 @@ class MetaModel(api.Meta):
             self._module = self._get_addon_name(self.__module__)
 
         # Remember which models to instanciate for this module.
-        if not self._custom:
+        if self._module:
             self.module_to_models[self._module].append(self)
 
         # check for new-api conversion error: leave comma after field definition