Steps to reproduce (an account with moderation rights needed):

1. Head to a question with several reply pages (e.g. https://support.mozilla.org/en-US/questions/1518939).
2. Go to any reply page except the first one (e.g. https://support.mozilla.org/en-US/questions/1518939?page=2).
3. Mark/unmark any reply on the page as spam.

Actual results:
The user is redirected to the initial question page (e.g. https://support.mozilla.org/en-US/questions/1518939) with the first reply page displayed.

Expected results:
The page (e.g. https://support.mozilla.org/en-US/questions/1518939?page=2) is reloaded, displaying the same reply page. The URL is not changed.