Mine

Index: subversion/bindings/swig/core.i
===================================================================
--- subversion/bindings/swig/core.i	(revision 16784)
+++ subversion/bindings/swig/core.i	(working copy)
@@ -632,7 +632,6 @@
 
 void svn_swig_py_set_application_pool(PyObject *py_pool, apr_pool_t *pool);
 void svn_swig_py_clear_application_pool();
-PyObject *svn_swig_py_register_cleanup(PyObject *py_pool, apr_pool_t *pool);
 
 %init %{
 /* Theoretically, we should be checking for errors here,
Index: subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c
===================================================================
--- subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c	(revision 16784)
+++ subversion/bindings/swig/python/libsvn_swig_py/swigutil_py.c	(working copy)
@@ -103,7 +103,6 @@
 static PyObject *_global_svn_swig_py_pool = NULL;
 static char assertValid[] = "assert_valid";
 static char parentPool[] = "_parent_pool";
-static char isValid[] = "_is_valid";
 static char wrap[] = "_wrap";
 static char unwrap[] = "_unwrap";
 static char setParentPool[] = "set_parent_pool";
@@ -136,50 +135,6 @@
   _global_svn_swig_py_pool = NULL;
 }
 
-/* Mark a pool as deleted after it is destroyed */
-static apr_status_t svn_swig_py_pool_destroyed(void *ptr)
-{
-  PyObject *pool = (PyObject *) ptr;
-  svn_swig_py_acquire_py_lock();
-  PyObject_DelAttrString(pool, isValid);
-  svn_swig_py_release_py_lock();
-  return APR_SUCCESS; 
-}
-
-/* Decrease a pool's reference count after it is destroyed */
-static apr_status_t svn_swig_py_pool_decref(void *ptr)
-{
-  PyObject *pool = (PyObject *) ptr;
-  svn_swig_py_acquire_py_lock();
-  Py_DECREF(pool);
-  svn_swig_py_release_py_lock();
-  return APR_SUCCESS; 
-}
-
-/* Register cleanup function */
-PyObject * svn_swig_py_register_cleanup(PyObject *py_pool, apr_pool_t *pool) 
-{
-  PyObject *result;
-  
-  svn_swig_py_acquire_py_lock();
-
-  /* Check that the pool object is valid */
-  result = PyObject_CallMethod(py_pool, assertValid, emptyTuple);
-  if (result == NULL) {
-    return NULL;
-  }
-  Py_DECREF(result);
-  svn_swig_py_release_py_lock();
-
-  /* Delete the "_isvalid" member when the pool is destroyed */
-  apr_pool_cleanup_register(pool, py_pool, svn_swig_py_pool_destroyed,
-                            apr_pool_cleanup_null);
-
-  /* Return None */
-  Py_INCREF(Py_None);
-  return Py_None;
-}
-
 /* Get the application pool */
 void svn_swig_get_application_pool(PyObject **py_pool, apr_pool_t **pool)
 {
@@ -203,6 +158,9 @@
       }
     } else {
       result = PyObject_CallMethod(pool, wrap, objectTuple, *proxy);
+      if (result == NULL) {
+        return 1;
+      }
       Py_DECREF(*proxy);
       *proxy = result;
     }
@@ -380,9 +338,6 @@
     return NULL;
   }
 
-  apr_pool_cleanup_register((apr_pool_t *)pool, py_pool, 
-    svn_swig_py_pool_decref, apr_pool_cleanup_null); 
-  
   if (proxy_set_pool(&py_pool, NULL)) {
     Py_DECREF(py_pool);
     return NULL;
Index: subversion/bindings/swig/include/proxy_apr.swg
===================================================================
--- subversion/bindings/swig/include/proxy_apr.swg	(revision 16784)
+++ subversion/bindings/swig/include/proxy_apr.swg	(working copy)
@@ -39,6 +39,10 @@
     self.assert_valid()
     return self.this
  
+def _mark_weakpool_invalid(weakpool):
+  if weakpool and weakpool() and hasattr(weakpool(), "_is_valid"):
+    del weakpool()._is_valid
+
 %}
 
 struct apr_pool_t {
@@ -61,9 +65,9 @@
         if not self._parent_pool:
           svn_swig_py_set_application_pool(self, self)
           application_pool = self
+
+        assert hasattr(self,"_wrap")
   
-        svn_swig_py_register_cleanup(self, self)
-  
       def valid(self):
         """Check whether this memory pool and its parents
         are still valid"""
@@ -91,13 +95,14 @@
   
         # Destroy pool
         self._apr_pool_destroy(self)
-  
+
         # Clear application pool if necessary
         if is_application_pool:
           application_pool = None
           self._svn_swig_py_clear_application_pool()
   
-        del self._parent_pool
+        # Mark self as invalid
+        del self._is_valid
   
       def __del__(self):
         """Automatically destroy memory pools, if necessary"""
@@ -106,9 +111,23 @@
   
       def _mark_valid(self):
         """Mark pool as valid"""
+
+        self._weakparent = None
+
         if self._parent_pool:
+          import weakref
+
           # Make sure that the parent object is valid
-          self._parent_pool.assert_valid();
+          self._parent_pool.assert_valid()
+
+          # Refer to self using a weakrefrence so that we don't
+          # create a reference cycle
+          weakself = weakref.ref(self)
+
+          # Set up callbacks to mark pool as invalid when parents
+          # are destroyed
+          self._weakparent = weakref.ref(self._parent_pool._is_valid,
+            lambda x: _mark_weakpool_invalid(weakself))
   
         # Mark pool as valid
         self._is_valid = lambda: 1