commit https://github.com/vim/vim/commit/2f97912800e86a296c001832bbbf2fc425f1e533 Author: Bram Moolenaar <Bram@vim.org> Date: Thu Oct 27 17:27:44 2016 +0200 patch 8.0.0049 Problem: When a match ends in part of concealed text highlighting, it might mess up concealing by resetting prev_syntax_id. Solution: Do not reset prev_syntax_id and add a test to verify. (Christian Brabandt, closes #1092)

the first targets to make vim are: scratch config myself
srcdir = .
VIMNAME = vim
EXNAME = ex
VIEWNAME = view