The spec file for tar claims that the source for it comes from ftp://ftp.gnu.org/pub/gnu/tar/tar-%{version}.tar.gz, but the latest version available in that location is 1.13, even though what's currently being shipped in the RPM is 1.13.16. I dug around a bit but was unable to figure out where the source is actually coming from. The spec file should identify the actual location from which the source came.
Thanks, fixed. The actual download location is alpha.gnu.org/gnu/tar We're using the so-called alpha version because it fixes a number of disturbing bugs that are still present in the "stable" version.