if ($http_user_agent ~ "MSIE 6.0" || $http_user_agent ~ "MSIE 7.0" (etc, etc)) {
    rewrite ^ ${ROOT_ROOT}ancient/ last;
   break;
}

if ($http_user_agent ~ "MSIE 6.0") {
    rewrite ^ ${ROOT_ROOT}ancient/ last;
   break;
}
if ($http_user_agent ~ "MSIE 7.0") {
    rewrite ^ ${ROOT_ROOT}ancient/ last;
   break;
}

if ($http_user_agent ~ "MSIE [67].")

set $test 0;
if ($http_user_agent ~ "MSIE 6.0") {
  set $test 1;
}
if ($http_user_agent ~ "MSIE 7.0") {
  set $test 1;
}
if ($test = 1) {
  rewrite ^ ${ROOT_ROOT}ancient/ last;
}

if ($http_user_agent ~ "(MSIE 6.0)|(MSIE 7.0)") {
  rewrite ^ ${ROOT_ROOT}ancient/ last;
}