commit https://github.com/vim/vim/commit/6244a0fc29163ba1c734f92b55a89e01e6cf2a67 Author: Bram Moolenaar <Bram@vim.org> Date: Thu Apr 14 14:09:25 2016 +0200 patch 7.4.1729 Problem: The Perl interface cannot use 'print' operator for writing directly in standard IO. Solution: Add a minimal implementation of PerlIO Layer feature and try to use it for STDOUT/STDERR. (Damien)

" Tests for :undo

func Test_ex_undo()
  new ex-undo
  setlocal ul=10
  exe "normal ione\n\<Esc>"
  setlocal ul=10
  exe "normal itwo\n\<Esc>"
  setlocal ul=10
  exe "normal ithree\n\<Esc>"
  call assert_equal(4, line('$'))
  undo
  call assert_equal(3, line('$'))
  undo 1
  call assert_equal(2, line('$'))
  undo 0
  call assert_equal(1, line('$'))
  quit!
endfunc