Currently, single_button ignores the anchor part of moodle_url. That leads to usability issues as we can not specify target anchors for continue buttons, confirmation/cancel buttons etc.

After discussed with Petr, this is triaged for STABLE and will be available only for single_buttons working via GET method (when using POST, we should redirect away and not to stay at the anchor).

The usability benefit of this patch is demonstrated in the new activity module duplication tool where the user is redirected to the relevant course section.