Both implementations of thin_metadata_size believe units are defined
like this:
1024 == kilobyte == k
1000 == kibibyte == K
and so on. Fix the 1000/1024 confusion, while continuing to follow the
LVM convention of using lowercase letters for binary units, so that we
have:
1024 == kibibyte == k
1000 == kilobyte == K
2679e7f088