nvim: git/fugitive: Add helper for git branch and checkout

nvim/.config/nvim/after/ftplugin/git.vim

@@ -1,2 +1,11 @@
 " Disable whitespace highlighting in git buffer
 autocmd BufEnter <buffer> DisableWhitespace
+
+xnoremap <Leader>gb :<C-U>call <SID>git_checkout_branch()<CR>
+
+" We would like to checkout a branch by visually selecting a branch name in
+" the output of git branch -a.
+function! s:git_checkout_branch() abort
+  normal! `<v`>y
+  silent execute "Git checkout " . shellescape(@@)
+endfunction

nvim/.config/nvim/after/plugin/fugitive.vim

@@ -1,5 +1,7 @@
 nnoremap <Leader>ga :Git fetch --all<CR>
 xnoremap <Leader>gb :Git blame<CR>
+nnoremap <Leader>gb :Git branch<SPACE>
+nnoremap <Leader>gB :Git checkout -b<SPACE>
 nnoremap <Leader>gd :Ghdiffsplit!<CR>
 nnoremap <Leader>gD :Gvdiffsplit!<CR>
 nnoremap <Leader>gs :Git<CR>