commit https://github.com/vim/vim/commit/b681be175b6991cdc2b8ddd49b0e97e3fe2b201e Author: Bram Moolenaar <Bram@vim.org> Date: Thu Mar 31 23:02:16 2016 +0200 patch 7.4.1691 Problem: When switching to a new buffer and an autocommand applies syntax highlighting an ml_get error may occur. Solution: Check "syn_buf" against the buffer in the window. (Alexander von Buddenbrock, closes #676)

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