This kind of works, except it eats the \n at the end

int cmd_uni()
{
    object tp = this_player() ;
    string mess = "" ;

    mess += "\u2501\n" ;

    write(mess) ;
    say(mess) ;

    return 1 ;
}

This is not consistent, however, since in other cases, it gives the error Illegal unicode sequence.

Tracked down to lex.cc -