I looked at that patch, and although it's moving in the right direction, it's not yet ready for prime-time. One can easily defeat its checking with a tarball that omits the second top-level directory (but contains the second directory's subsidiary files). Or one could simply make the top level "." or "..".
A lesser thing: it's missing a NEWS entry. Although checking like this might be a good idea, it needn't hold up the next release.
