commit https://github.com/vim/vim/commit/17a13437c9414a8693369a97f3be2fc8ad48c12e Author: Bram Moolenaar <Bram@vim.org> Date: Sun Jan 24 14:22:10 2016 +0100 patch 7.4.1163 Problem: Expressions "0 + v:true" and "'' . v:true" cause an error. Solution: Return something sensible when using a special variable as a number or as a string. (suggested by Damien)

Results of test106:
[['W', 1], ['E^@CCCC', 1]]
[['W', 1], ['E^@CCCC', 1]]
[['W', 1], ['ZZZZ', 0], ['E^@CCCC', 1], ['YYYY', 0]]