I would like this feature too. I've attached a patch that I think should
work and then a very basic test case.

Also the following files should be added from GNU tar:

  /* Arch.  */
  ".arch-ids",
  "{arch}",
  "=RELEASE-ID",
  "=meta-update",
  "=update",
  /* Bazaar.  */
  ".bzr",
  ".bzrignore",
  ".bzrtags",

But I haven't used those version control systems so I am unsure which
ones are directories or not.

Thanks,
Collin