Hi, I just came across this issue with GNU tar 1.26. I noticed that the problem was previously reported in 2004 but it's still present in the current tar release. See http://lists.gnu.org/archive/html/bug-tar/2004-06/msg00000.html
Basically, when you specify --format=v7, GNU tar creates archives with entries for directories, which is incorrect. They should be omitted from v7-format archives.
