patch 8.2.0906: when setting 'termguicolors' SpellBad is no longer red Commit: https://github.com/vim/vim/commit/ea563cc22be043ff91dcbdf2878c3d1fd944e573 Author: Bram Moolenaar <Bram@vim.org> Date: Fri Jun 5 19:36:57 2020 +0200 patch 8.2.0906: when setting 'termguicolors' SpellBad is no longer red Problem: When setting 'termguicolors' SpellBad is no longer red. Solution: Only use the RGB guisp color for cterm when using the "underline" or "undercurl" attributes to avoid the background color to be cleared. Also make t_8u empty when the termresponse indicates a real xterm. (closes #6207)