Traceback (most recent call last):
  File "/usr/share/software-center/softwarecenter/view/appview.py", line 510, in on_get_value
    if pkgname in self.cache and self.cache[pkgname].is_installed:
  File "/usr/share/software-center/softwarecenter/apt/aptcache.py", line 101, in __contains__
    return self._cache.__contains__(k)
AttributeError: 'NoneType' object has no attribute '__contains__'