commit https://github.com/vim/vim/commit/7e47d1ac6a9ae0e5a7167aa34ff651a9c39c1641 Author: Bram Moolenaar <Bram@vim.org> Date: Tue Aug 25 16:19:05 2015 +0200 patch 7.4.834 Problem: gettabvar() doesn't work after Vim start. (Szymon Wrozynski) Solution: Handle first window in tab still being NULL. (Christian Brabandt)

" Settings for test script execution
" Always use "COMMAND.COM", don't use the value of "$SHELL".
set shell=c:\COMMAND.COM shellquote= shellxquote= shellcmdflag=/c shellredir=>
" This is used only when the +eval feature is available.
if executable("cmd.exe")
   set shell=cmd.exe
endif