[Bug-tar] incremental backups--full backup after upgrading to newer tar

[Andrew Henry]

I run three levels of incremental backups using 3 different snar files.

I upgraded to a newer version of my distro that has tar 1.19 and now my
level 1 and level 2 incrementals do not work anymore, instead they do a
full level 0 backup.

I have performed an incremental restore with my backups after having
wiped my disc and installed the newer distro, which worked perfectly.  I
had restored my snar files under /var/log/backups and they had retained
their creation dates, as have my files under /home (the directory i backup).

The previous version of tar on the old distro version was 1.18.

Is my assumption correct that tar cannot use snar files from previous
versions of tar?  Why not?  It is a bit annoying that I cannot keep my
backup scheme, and must create new backup sets.

regards,
andrew.