Merge branch 'jn/warn-on-inaccessible-loosen'

Deal with a situation where .config/git is a file and we notice .config/git/config is not readable due to ENOTDIR, not ENOENT. * jn/warn-on-inaccessible-loosen: config: exit on error accessing any config file doc: advertise GIT_CONFIG_NOSYSTEM config: treat user and xdg config permission problems as errors config, gitignore: failure to access with ENOTDIR is ok