I checked do-release-upgrade -d before upgrading apt, and pressing Ctrl+C at the prompt for conforming changes left hirsute in sources.list.
I upgraded to apt 2.1.10ubuntu0.3 from proposed, ran it again, and Ctrl+C now caused the restore code to run:
Continue [yN] Details [d]^C
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
=== Command detached from window (Tue Mar 30 15:04:31 2021) ===
I checked do-release-upgrade -d before upgrading apt, and pressing Ctrl+C at the prompt for conforming changes left hirsute in sources.list.
I upgraded to apt 2.1.10ubuntu0.3 from proposed, ran it again, and Ctrl+C now caused the restore code to run:
Continue [yN] Details [d]^C
Restoring original system state
Aborting
Reading package lists... Done
Building dependency tree
Reading state information... Done
=== Command detached from window (Tue Mar 30 15:04:31 2021) ===