software-center-gtk3 crashed with AttributeError in rebuild_categorised_view(): 'NoneType' object has no attribute 'query'

This bug was fixed in the package software-center - 4.1.22

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software-center (4.1.22) oneiric; urgency=low

  [ Gary Lasker ]
  * data/ubuntu-software-center.desktop.in,
    debian/rules,
    setup.py,
    software-center,
    software-center-gtk2,
    softwarecenter/toolkit.py:
    - launch the new UI using 'software-center', add script
      to launch the old version if feeling nostalgic (LP: #839257)
  * softwarecenter/ui/gtk3/views/appdetailsview_gtk.py:
    - fix incorrect ellipsize for title and summary in the
      details view (LP: #842271)
  * softwarecenter/ui/gtk3/panes/availablepane.py,
    softwarecenter/ui/gtk3/session/viewmanager.py:
    - hide the search field when in the purchase
      view (LP: #844883)
  * softwarecenter/ui/gtk3/views/catview_gtk.py:
    - don't create the what's new panel if we don't have the
      corresponding category (LP: #835129)
  * softwarecenter/ui/gtk3/panes/installedpane.py:
    - fix crash in rebuild_categorised_view while viewing
      installed items (LP: #834260)
  * test/gtk3/test_catview.py,
    test/gtk3/test_panes.py,
    test/test_addons.py,
    test/test_package_info.py:
    - fix unit tests
  * setup.py:
    - fix build error when merging authors list
  * merged lp:~gary-lasker/software-center/pyflakes-fixes, no
    user visible changes, only code cleanup
  * po/software-center.pot:
    - refresh .pot file

  [ Matthew McGowan ]
  * data/ui/gtk3/css/softwarecenter.css,
    softwarecenter/ui/gtk3/views/appdetailsview_gtk.py:
    - fix grey addon label, only pkgname should be grey
      (LP: #838607)
  * softwarecenter/ui/gtk3/widgets/description.py,
    softwarecenter/utils.py,
    test/test_description_norm.py:
    - description formatting improvements, update unit test
  * data/ui/gtk3/css/softwarecenter.css,
    softwarecenter/ui/gtk3/widgets/cellrenderers.py:
    - use css to set border-radius of cellrenderer button
  * softwarecenter/ui/gtk3/views/appview.py:
    - disable appcount display at the bottom of list views
      for now to allow keyboard scrolling to work (LP: #830258)
  * lp:~mmcg069/software-center/lobby-tweaks:
    - restore tile borders but disable the checkerboard
      rendering, color tweaks and other improvements to the
      title area visuals
  * merge lp:~mmcg069/software-center/image-data-cleanup:
    - cleanup unused image files (LP: #839736)
  * softwarecenter/ui/gtk3/panes/softwarepane.py:
    - fix doubled search results (LP: #840235)
  * softwarecenter/ui/gtk3/app.py:
    - fix "Copy Web Link" feature (LP: #830291)

  [ Andrea Cimitan ]
  * softwarecenter/ui/gtk3/widgets/symbolic_icons.py:
    - Fix blurriness of toolbar icons, reduce shadow alpha level

  [ Gabor Kelemen ]
  * po/POTFILES.in:
    - additional i18n fixes (LP: #836346)

  [ Kiwinote ]
  * remove the old webkit ui
  * remove the need for dummy-screenshot-ubuntu.png (LP: #837223)
  * data/ui/gtk3/SoftwareCenter.ui,
    softwarecenter/ui/gtk3/app.py:
    - make all the accelerators work again (LP: #640426, LP: #660050,
      LP: #828233, LP: #830238, LP: #834988, LP: #843682)
      also fixes (LP: #823094, LP: #837062)
  * softwarecenter/db/appfilter.py,
    softwarecenter/ui/...