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)

" 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