function to regenerate itself with a different setup script. This
is useful for experimenting with changes to the setup script in
specific packages without triggering a rebuild of everything.
* stdenv/generic/setup-latest.sh is a branch of setup.sh containing
pending changes that will be merged into setup.sh eventually.
* setup-latest.sh: don't use tar's "z" and "j" flags. Rather, call
gzip and bunzip2 directly.
svn path=/nixpkgs/trunk/; revision=6066
