Comment 5 for bug 1826213

A hackish test case for this bug involves the following:

1) edit the MyCache class's __init__ function (found in UpdateManager/Core/MyCache.py) to 'raise AssertionError' which will simulate having a dirty journal or broken packages
2) comment out 'self.window_main.duplicate_packages = self.get_deb2snap_dups()' in UpdateManager/backend/__init__.py as that will also Traceback on an AssertionError with the Traceback seen in bug 1880987

Having made those changes you'll get the Traceback in this bug and with the version from -proposed you'll see a 'Not all updates can be installed' dialog.