Testing with just Breaks/Replaces (without << version) removes python-swauth on upgrade from xenial->bionic. The same occurs with Breaks/Replaces (without << version) and the dummy python-swauth package defined. Once the << versions are added to the Breaks/Replaces the dummy transitional package properly remains after upgrade.
Ok so turns out all of the above in comment #8 is required for a clean upgrade that results in: https:/ /paste. ubuntu. com/p/KfRdCD4Cq B/.
Testing with just Breaks/Replaces (without << version) removes python-swauth on upgrade from xenial->bionic. The same occurs with Breaks/Replaces (without << version) and the dummy python-swauth package defined. Once the << versions are added to the Breaks/Replaces the dummy transitional package properly remains after upgrade.