g:ack_default_options only applied if g:ackprg

[Konfekt]

In documentation, note that g:ack_default_options only applied if g:ackprg unset!

Thanks to

if !exists("g:ackprg")
  if executable('ack')
    let g:ackprg = "ack"
  elseif executable('ack-grep')
    let g:ackprg = "ack-grep"
  else
    finish
  endif
  let g:ackprg .= g:ack_default_options
endif

the g:ack_default_options are only applied if g:ackprg is unset.

Either

• note this in the documentation (and explain that the options can be passed directly to g:ackprg), or
• apply these options even if g:ack_default_options is set.

[ches]

#152 will resolve this, if that pull request doesn't get rebased soon then I'll address it myself. So I'm going to close this issue in favor of that issue/PR, but I'd like to understand use cases for having both g:ackprg and g:ack_default_options exist—if you could please comment on #152 about how you use them I'd appreciate it!