There is no local foldopen/close. See Vim doc.

If insist on this functionality, try adding
```
autocmd BufReadPost quickfix call s:qfEnter()
autocmd WinLeave * call s:qfLeave()
function! s:qfEnter()
  let g:oldfc=&foldclose
  let g:oldfo=&foldopen
  set foldclose=all
  set foldopen=all
endfunction
function! s:qfLeave()
  if &filetype!='qf'
    return
  endif
  set foldclose=g:oldfc
  set foldopen=g:oldfo
endfunction
```
to `plugin\ack.vim`.