This broke because /dev/mapper/ubuntu-swap_1 is now a symlink to /dev/dm-1, and /dev/dm-1 is what's in /proc/swaps, but partman-basicfilesystems' grep misses that.
This broke because /dev/mapper/ ubuntu- swap_1 is now a symlink to /dev/dm-1, and /dev/dm-1 is what's in /proc/swaps, but partman- basicfilesystem s' grep misses that.