preview options delimiter with depth breaks preview window

- [ x] I have fzf 0.30.0 or above
- [ x] I have read through https://github.com/junegunn/fzf.vim/blob/master/README.md
- [ x] I have read through https://github.com/junegunn/fzf/blob/master/README-VIM.md
- [ x] I have read through the manual page of fzf (`man fzf`)
- [ x] I have searched through the existing issues

#### Issue
Preview window does not show the line correctly when used with `'--delimiter', '/', '--with-nth', '-2..']`

#### What I try to achieve
Wrap or shorten long path names so matches can be more readable

example:

#### What I tried
I used base confing from [advanced ripgrep integration](https://github.com/junegunn/fzf.vim/blob/master/doc/fzf-vim.txt) then according to this issue https://github.com/junegunn/fzf.vim/issues/741 I add `'--delimiter', '/', '--with-nth', '-2..']` to my config that looks like

```

command! -bang -nargs=* Rg
\ call fzf#vim#grep(
\ 'rg --column --line-number --no-heading --color=never --smart-case '.shellescape(), 1,
\ fzf#vim#with_preview(), 0)

function! RipgrepFzf(query, fullscreen)
let command_fmt = 'rg -g "*.yml" -g "*.cs" -g "*.cpp" -g "*.h" --column --line-number --no-heading --color=always --smart-case %s | sed "s/ \{1,\}/ /g" || true'
let initial_command = printf(command_fmt, shellescape(a:query))
let reload_command = printf(command_fmt, '{q}')
let spec = {'options': ['--phony', '--query', a:query, '--bind', 'change:reload:'.reload_command, '--delimiter', '/', '--with-nth', '-2..']}
call fzf#vim#grep(initial_command, 1, fzf#vim#with_preview(spec), a:fullscreen)
endfunction

command! -nargs=* -bang RG call RipgrepFzf(, 0)
]])

```

After that issue looks like this instead showing the line that words placed in it only shows beginning of the file