update-manager fails to start

[Miyo]

Binary package hint: update-manager

$ update-manager
Traceback (most recent call last):
  File "/usr/bin/update-manager", line 29, in <module>
    import gtk
  File "/var/lib/python-support/python2.6/gtk-2.0/gtk/__init__.py", line 38, in <module>
    import gobject as _gobject
  File "/var/lib/python-support/python2.6/gtk-2.0/gobject/__init__.py", line 33, in <module>
    from glib import spawn_async, idle_add, timeout_add, timeout_add_seconds, \
  File "/var/lib/python-support/python2.6/gtk-2.0/glib/__init__.py", line 30, in <module>
    from glib._glib import *
ImportError: /var/lib/python-support/python2.6/gtk-2.0/glib/_glib.so: undefined symbol: PyUnicodeUCS4_DecodeUTF8

$ lsb_release -rd
Description: Ubuntu jaunty (development branch)
Release: 9.04

$ uname -a
Linux aurae 2.6.28-11-generic #37-Ubuntu SMP Mon Mar 23 16:40:00 UTC 2009 x86_64 GNU/Linux