commit https://github.com/vim/vim/commit/2932359000b2f918d5fade79ea4d124d5943cd07 Author: Bram Moolenaar <Bram@vim.org> Date: Sun Jul 24 22:04:11 2016 +0200 patch 7.4.2101 Problem: Looping over windows, buffers and tab pages is inconsistant. Solution: Use FOR_ALL_ macros everywhere. (Yegappan Lakshmanan)

" Common preparations for running tests.

" Make sure 'runtimepath' does not include $HOME.
set rtp=$VIM/vimfiles,$VIMRUNTIME,$VIM/vimfiles/after

" Only when the +eval feature is present. 
if 1
  " Make sure $HOME does not get read or written.
  let $HOME = '/does/not/exist'
endif