Index: subversion/bindings/swig/include/svn_types.swg
===================================================================
--- subversion/bindings/swig/include/svn_types.swg	(revision 30564)
+++ subversion/bindings/swig/include/svn_types.swg	(working copy)
@@ -252,6 +252,7 @@
                           PythonThunk, PerlThunk, RubyThunk)
 %typemap(in) (CallbackFunction, CallbackBaton) {
   $1 = PythonThunk;
+  Py_INCREF($input);
   $2 = $input;
 }
 %enddef