Merge pull request #66992 from oxij/nixos/fix-zsh-prompt

nixos: zsh: setopt prompt_sp to workaround a zsh bug

nixos/modules/programs/zsh/zsh.nix

···
       promptInit = mkOption {
         default = ''
           if [ "$TERM" != dumb ]; then
-              autoload -U promptinit && promptinit && prompt walters
+              autoload -U promptinit && promptinit && prompt walters && setopt prompt_sp
           fi
         '';
         description = ''