Running `rake install`, runs the `:submodule_init` task,
which in turn runs the following command:
git submodule update --init --recursive
This fails with the following couple of errors (separately):
No submodule mapping found in .gitmodules for path 'vim/bundle/mattn-zencoding-vim'
No submodule mapping found in .gitmodules for path 'vim/bundle/skwp-vim-indexed-search'
This was introduced by 3d60f721dd
which removed the 'mattn/zencoding-vim' and 'skwp/vim-indexed-search'
submodules from the `.gitmodules`.
