What is the procedure to continue or retry a "do-release-upgrade" after it has failed on something, and that has been fixed?
While upgrading from 15.10 to 16.04 LTS, mysql failed to upgrade, and the upgrade quit before finishing, leaving the system in a partially upgraded state.
The steps in this article fixed it, and MySQL is running now:
16.04 upgrade broke mysql-server
What do I need to do next, to continue the upgrade, have do-release-upgrade finish whatever steps need to be completed, and have the system usable again?
