Reset __attrs_own_setattr__ along with __setattr__

Signed-off-by: Hynek Schlawack <hs@ox.cx>

src/attr/_make.py

@@ -655,6 +655,7 @@ def _patch_original_class(self):
             cls, "__attrs_own_setattr__", False
         ):
             cls.__setattr__ = object.__setattr__
+            cls.__attrs_own_setattr__ = False
 
         return cls
 
@@ -669,9 +670,10 @@ def _create_slots_class(self):
             if k not in tuple(self._attr_names) + ("__dict__", "__weakref__")
         }
 
-        # If our class doesn't have an own __setattr__ (either from the user or
-        # by us), check the bases, if one of them has an attrs-made
-        # __setattr__, that needs to be reset.
+        # If our class doesn't have its own implementation of __setattr__
+        # (either from the user or by us), check the bases, if one of them has
+        # an attrs-made __setattr__, that needs to be reset. We don't walk the
+        # MRO because we only care about our immediate base classes.
         # XXX: This can be confused by subclassing a slotted attrs class with
         # XXX: a non-attrs class and subclass the resulting class with an attrs
         # XXX: class.  See `test_slotted_confused for details.  For now that's
@@ -682,6 +684,7 @@ def _create_slots_class(self):
             for base_cls in getattr(self._cls, "__bases__", ()):
                 if base_cls.__dict__.get("__attrs_own_setattr__", False):
                     cd["__setattr__"] = object.__setattr__
+                    cd["__attrs_own_setattr__"] = False
                     break
 
         # Traverse the MRO to check for an existing __weakref__.

tests/test_setattr.py

@@ -227,6 +227,9 @@ class NoHook(WithOnSetAttrHook):
             assert NoHook.__setattr__ == object.__setattr__
 
         assert 1 == NoHook(1).x
+        assert Hooked.__attrs_own_setattr__
+        assert not NoHook.__attrs_own_setattr__
+        assert WithOnSetAttrHook.__attrs_own_setattr__
 
     @pytest.mark.parametrize("slots", [True, False])
     def test_setattr_inherited_do_not_reset(self, slots):