Fix no_split and no_buffer

This seems to fix recent changes introduce in Unite regarding [no_split](https://github.com/Shougo/unite.vim/commit/4ef321ba2c53451dfab8ec548917c07b81a76d5e) and [no_buffer](https://github.com/Shougo/unite.vim/commit/d2613e981879ef2948fc3460413e27679ff8cdd8).