commit https://github.com/vim/vim/commit/ba61ac0d61f46de7d29c64bb0de6d25c2e378be0 Author: Bram Moolenaar <Bram@vim.org> Date: Sun Mar 20 16:40:37 2016 +0100 patch 7.4.1617 Problem: When a JSON message is split it isn't decoded. Solution: Wait a short time for the rest of the message to arrive.

" 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