patch 8.1.0513: no error for set diffopt+=algorithm: commit https://github.com/vim/vim/commit/d0721058f494143186f66a60151c9634031a8c96 Author: Bram Moolenaar <Bram@vim.org> Date: Mon Nov 5 21:21:33 2018 +0100 patch 8.1.0513: no error for set diffopt+=algorithm: Problem: No error for set diffopt+=algorithm:. Solution: Check for missing argument. (Hirohito Higashi, closes https://github.com/vim/vim/issues/3598)