Comment 1 for bug 1842437

Problem:

- the ext4 filesystem is detected correctly at the beginning of the partition.
- the nilfs2 filesystem is detected incorrectly at the end of the partition.
- the nilfs2 checksum is invalid, but that is ignored by udev builtin blkid.
- the detection of more than one filesystems causes an error and stop blkid.

# LIBBLKID_DEBUG=all udevadm test-builtin blkid /sys/block/loop0/loop0p1
...
30555: libblkid: LOWPROBE: [28] ext4:
30555: libblkid: LOWPROBE: reuse buffer: off=1024 len=1024 pr=0x558f3ea3dec0
30555: libblkid: LOWPROBE: magic sboff=56, kboff=1
30555: libblkid: LOWPROBE: call probefunc()
30555: libblkid: LOWPROBE: reuse buffer: off=1024 len=1024 pr=0x558f3ea3dec0
30555: libblkid: PROBE: ext2_sb.compat = 0000003C:00000246:0000007B
30555: libblkid: LOWPROBE: assigning UUID [superblocks]
30555: libblkid: LOWPROBE: assigning VERSION [superblocks]
30555: libblkid: LOWPROBE: assigning TYPE [superblocks]
30555: libblkid: LOWPROBE: assigning USAGE [superblocks]
...
30555: libblkid: LOWPROBE: [63] nilfs2:
30555: libblkid: LOWPROBE: call probefunc()
30555: libblkid: LOWPROBE: reuse buffer: off=1024 len=1024 pr=0x558f3ea3dec0
30555: libblkid: LOWPROBE: reuse buffer: off=1072689152 len=4096 pr=0x558f3ea3dec0
30555: libblkid: LOWPROBE: incorrect checksum for type nilfs2, got 3F8DC6BA, expected 2D2D206B
30555: libblkid: LOWPROBE: assigning SBBADCSUM [superblocks]
30555: libblkid: LOWPROBE: nilfs2: primary=0, backup=1, swap=1
30555: libblkid: LOWPROBE: assigning LABEL [superblocks]
30555: libblkid: LOWPROBE: assigning UUID [superblocks]
30555: libblkid: LOWPROBE: assigning VERSION [superblocks]
30555: libblkid: LOWPROBE: assigning TYPE [superblocks]
30555: libblkid: LOWPROBE: assigning USAGE [superblocks]
...
30555: libblkid: LOWPROBE: ERROR: superblocks chain: ambivalent result detected (2 filesystems)!
...

# echo $?
1