Comment 22 for bug 1858802

Verification done on eoan-proposed.
Now libblkid1 detects only the bcache superblock and prints udev/uuid variables.

$ lsb_release -cs
eoan

$ DISK_IMG=disk.img
$ rm -f $DISK_IMG
$ dd if=/dev/zero of=$DISK_IMG bs=1G count=0 seek=1
$ BACKING_DEV=$(sudo losetup --find --show $DISK_IMG)
$ sudo make-bcache -B $BACKING_DEV
$ BCACHE_DEV="$(readlink -e /sys/block/$(basename $BACKING_DEV)/bcache/dev)"
$ BCACHE_DEV="/dev/$(basename $BCACHE_DEV)"
$ sudo mkfs.xfs -d agsize=16m -l agnum=0 -f $BCACHE_DEV
$ echo 1 | sudo tee /sys/block/$(basename $BCACHE_DEV)/bcache/stop

$ sudo hexdump -C $BACKING_DEV | grep -m2 -e XFSB -e 'fe ed ba be'
00002000 58 46 53 42 00 00 10 00 00 00 00 00 00 03 f0 00 |XFSB............|
00007000 fe ed ba be 00 00 00 01 00 00 00 02 00 00 02 00 |................|

eoan-updates:
---

$ dpkg -s libblkid1 | grep -i version:
Version: 2.34-0.1ubuntu2.1

$ sudo blkid -o udev -p $BACKING_DEV
ID_FS_AMBIVALENT=other:bcache other:xfs_external_log

eoan-proposed:
---

$ apt-cache madison libblkid1 | grep proposed
 libblkid1 | 2.34-0.1ubuntu2.2 | http://archive.ubuntu.com/ubuntu eoan-proposed/main amd64 Packages

$ sudo apt install libblkid1 -y

$ dpkg -s libblkid1 | grep -i version:
Version: 2.34-0.1ubuntu2.2

$ sudo blkid -o udev -p $BACKING_DEV
ID_FS_UUID=55bac736-a3dc-4d9a-80e9-330ba46dd97d
ID_FS_UUID_ENC=55bac736-a3dc-4d9a-80e9-330ba46dd97d
ID_FS_TYPE=bcache
ID_FS_USAGE=other