Merge pull request #9291 from vincentbernat/fix/zsh-completion-update-2

zsh: correctly parse available subcommands (completion)

contrib/completion/zsh/_docker

@@ -177,7 +177,9 @@ __docker_commands () {
     if ( [[ ${+_docker_subcommands} -eq 0 ]] || _cache_invalid docker_subcommands) \
         && ! _retrieve_cache docker_subcommands;
     then
-        _docker_subcommands=(${${${${(f)"$(_call_program commands docker 2>&1)"}[5,-1]}## #}/ ##/:})
+        local -a lines
+        lines=(${(f)"$(_call_program commands docker 2>&1)"})
+        _docker_subcommands=(${${${lines[$((${lines[(i)Commands:]} + 1)),${lines[(I)    *]}]}## #}/ ##/:})
         _docker_subcommands=($_docker_subcommands 'help:Show help for a command')
         _store_cache docker_subcommands _docker_subcommands
     fi