The idea of downloading the source code tarball directly from gitorious.org was
great, but didn't work. Apparently, those tarballs have different checksums
every time they're generated. To remedy the situation, I've copied the proper
tarball statically to <http://cryp.to/magit-mainline-0.7-94-gbf42bf8.tar.gz>.
svn path=/nixpkgs/trunk/; revision=20653