inside/vim-grep-operator — pull request #1 by mjwhitta (2014-08-10 16:12:03+00:00)
Title: Added support for Ag.vim and Ack.vim

Added a variable that lets the user specify if they would prefer to use ag (the_silver_searcher) or ack instead of grep. If Ag.vim/Ack.vim is not installed, or ag/ack is not installed, then it falls back to grep.