The vim-colors-solarized repo is a subtree of the solarized repo. This is mostly a convenience for vim users that use something like pathogen + git-submodule to keep their plugins up-to-date. This way you can create a submodule @ ~/.vim/bundle/vim-colors-solarized and it would be the root of the bundle tree. If the vim colorscheme was only part of the larger repo, then users would be forced to create their own repos, or else do something like:
