<http://match.stanford.edu/gnugo/archive/gnugo-3.9.1.tar.gz>: The requested URL /gnugo/archive/gnugo-3.9.1.tar.gz was not found on this server.
+1 The files is a bit hard to find, as it seems to have been removed from upstream. If anyone needs it, I have placed a copy at: http://dotslash.ca/files/gentoo/gnugo-3.9.1.tar.gz
available at http://git.savannah.gnu.org/cgit/gnugo.git/snapshot/rel-3-9-1.tar.gz too bad development has stalled...
This was fixed some time ago: 18 Mar 2014; Michael Sterrett <mr_bones_@gentoo.org> gnugo-3.9.1.ebuild: archive file disappeared upstream