Attachment deletion fails (https/http mixed content)

All links in the Attachments box of a page (name, authors, actions) are generated with "http://" scheme. We serve XWiki via https (via Apache httpd proxy). The browser does thus not allow links to http:// content (https://developer.mozilla.org/en-US/docs/Web/Security/Mixed_content) so the request to delete or move attachments will not be executed and a failure message appears.

The workaround right now is to copy the move/delete links and add https:// at the front.