tpope/vim-fugitive — pull request #586 by Konfekt (2014-12-14 11:37:47+00:00)
Title: use same escaping for cmd and powershell

Powershell, just like cmd, uses doubled double quotation marks
to escape double quotation marks. Therefore s:shellesc() should
take account of cmd and powershell as well.

This was discussed at https://github.com/tpope/vim-fugitive/issues/435