Traceback (most recent call last):
  File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 798, in _on_backend_done
    self.fillstore()
  File "/usr/lib/python2.7/dist-packages/UpdateManager/UpdateManager.py", line 982, in fillstore
    self.list.update(self.cache)
  File "/usr/lib/python2.7/dist-packages/UpdateManager/Core/UpdateList.py", line 80, in update
    self.distUpgradeWouldDelete = cache.saveDistUpgrade()
  File "/usr/lib/python2.7/dist-packages/UpdateManager/Core/MyCache.py", line 103, in saveDistUpgrade
    assert self._depcache.broken_count == 0 and self._depcache.del_count == 0
AssertionError