Empty CmdWin Bufname

spec-vim-buffer.vim

scriptencoding utf-8
source spec/base.vim

let g:VB = vital#of('vital').import('Vim.Buffer')

Context Vim.Buffer.is_cmdwin()
  It detects if current window is cmdwin.
    " normal! q:
    let save_cedit = &cedit
    let &cedit = "<C-f>"
    try
      execute "normal! :\<C-f>\<CR>"
      Should g:VB.is_cmdwin()
      quit
      Should !g:VB.is_cmdwin()
    finally
      let &cedit = save_cedit
    endtry
  End
End

" (以下省略)

vim-buffer.vim

  let s:save_cpo = &cpo
set cpo&vim

function! s:_vital_loaded(V)
  let s:V = a:V
  let s:P = s:V.import('Prelude')
endfunction

function! s:_vital_depends()
  return ['Prelude']
endfunction

function! s:is_cmdwin()
  echom string(bufname('%'))
  sleep 5
  return bufname('%') ==# '[Command Line]'
endfunction

" (以下省略)