software-center crashes with AttributeError: No constructor defined

Binary package hint: software-center

software-center 3.1.4

software-center fails to launch in a fully updated Natty with the error
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Traceback (most recent call last):
  File "/usr/bin/software-center", line 109, in <module>
    app = SoftwareCenterApp(datadir, xapian_base_path, options, args)
  File "/usr/share/software-center/softwarecenter/app.py", line 209, in __init__
    self.navhistory_forward_action)
  File "/usr/share/software-center/softwarecenter/view/availablepane.py", line 97, in __init__
    self._build_ui()
  File "/usr/share/software-center/softwarecenter/view/availablepane.py", line 108, in _build_ui
    self.apps_filter)
  File "/usr/share/software-center/softwarecenter/view/catview_gtk.py", line 244, in __init__
    self.build(desktopdir)
  File "/usr/share/software-center/softwarecenter/view/catview_gtk.py", line 489, in build
    self._build_homepage_view()
  File "/usr/share/software-center/softwarecenter/view/catview_gtk.py", line 315, in _build_homepage_view
    self._append_featured_and_new()
  File "/usr/share/software-center/softwarecenter/view/catview_gtk.py", line 404, in _append_featured_and_new
    nonapps_visible=AppStore.NONAPPS_ALWAYS_VISIBLE)
  File "/usr/share/software-center/softwarecenter/view/appview.py", line 182, in __init__
    self._perform_search()
  File "/usr/share/software-center/softwarecenter/view/appview.py", line 249, in _perform_search
    enquire.set_sort_by_key(LocaleSorter(self.db), reverse=False)
  File "/usr/share/software-center/softwarecenter/view/appview.py", line 594, in __init__
    xapian.Sorter.__init__(self)
  File "/usr/lib/python2.6/dist-packages/xapian/__init__.py", line 5620, in __init__
    def __init__(self, *args, **kwargs): raise AttributeError("No constructor defined")
AttributeError: No constructor defined