*** typeobject.c.orig	Tue Dec 31 08:33:00 2002
--- typeobject.c	Tue Feb  4 11:32:12 2003
***************
*** 144,149 ****
--- 144,150 ----
  static PyTypeObject *best_base(PyObject *);
  static int mro_internal(PyTypeObject *);
  static int compatible_for_assignment(PyTypeObject *, PyTypeObject *, char *);
+ static int bases_compatible_for_assignment(PyTypeObject *, PyTypeObject *);
  static int add_subclass(PyTypeObject*, PyTypeObject*);
  static void remove_subclass(PyTypeObject *, PyTypeObject *);
  static void update_all_slots(PyTypeObject *);
***************
*** 241,247 ****
  		return -1;
  	}
  
! 	if (!compatible_for_assignment(type->tp_base, new_base, "__bases__"))
  		return -1;
  
  	Py_INCREF(new_base);
--- 242,248 ----
  		return -1;
  	}
  
! 	if (!bases_compatible_for_assignment(type->tp_base, new_base))
  		return -1;
  
  	Py_INCREF(new_base);
***************
*** 2300,2305 ****
--- 2301,2333 ----
  }
  
  static int
+ bases_compatible_for_assignment(PyTypeObject *old, PyTypeObject *new)
+ {
+     PyTypeObject *solidold, *solidnew;
+     
+     solidold = solid_base(old);
+     solidnew = solid_base(new);
+     
+     if (solidold == solidnew)
+     {
+         PyTypeObject *base;
+         destructor olddealloc, newdealloc;
+ 
+         base = old;
+         while ((olddealloc = base->tp_dealloc) == subtype_dealloc)
+             base = base->tp_base;
+ 
+         base = new;
+         while ((newdealloc = base->tp_dealloc) == subtype_dealloc)
+             base = base->tp_base;
+ 
+         if (olddealloc == newdealloc)
+             return 1;
+     }
+     return compatible_for_assignment(old, new, "__bases__");
+ }
+ 
+ static int
  object_set_class(PyObject *self, PyObject *value, void *closure)
  {
  	PyTypeObject *old = self->ob_type;