commit https://github.com/vim/vim/commit/0abe0522d0e52b50c6eab52323be558eb56fe95e Author: Bram Moolenaar <Bram@vim.org> Date: Sun Aug 28 16:53:12 2016 +0200 patch 7.4.2282 Problem: When a child process is very fast waiting 10 msec for it is noticeable. (Ramel Eshed) Solution: Start waiting for 1 msec and gradually increase.

" Test for joining lines.

func Test_join_with_count()
  new
  call setline(1, ['one', 'two', 'three', 'four'])
  normal J
  call assert_equal('one two', getline(1))
  %del
  call setline(1, ['one', 'two', 'three', 'four'])
  normal 10J
  call assert_equal('one two three four', getline(1))
  quit!
endfunc