commit https://github.com/vim/vim/commit/04c4ce650f9e533cd35b2aa6803f4d354d3ec7aa Author: Bram Moolenaar <Bram@vim.org> Date: Thu Sep 1 15:45:58 2016 +0200 patch 7.4.2299 Problem: QuickFixCmdPre and QuickFixCmdPost autocommands are not always triggered. Solution: Also trigger on ":expr", ":cbuffer", etc. (Yegappan Lakshmanan)

start:
test for empty string: ok
test for 1 char: ok
test for 3 chars: ok
test for contains meta char: ok
test for contains non-ascii char: ok