I really don't like submodules in Git. There's a much better way:
$ git remote add -f svbhack https://github.com/gfidente/pelican-svbhack.git
$ git merge -s ours --no-commit svbhack/master
$ git read-tree --prefix=themes/svbhack -u svbhack/master
$ echo "THEME = 'themes/svbhack'" > pelicanconf.py
$ git commit -m 'Import svbhack theme'