Commenting on an Ajax updated post redirects to a page showing "0"

[duduweiland]

In a freshly installed Wordpress 3.5 with BuddyPress 1.6.2 with default theme and no other plugins:

1. Post some status update. This will be posted using Ajax and then loaded into the Activity timeline.
2. Comment on the Ajax-updated post. This will not use Ajax and will redirect to a URL like ​http://domain.com/wp-admin/admin-ajax.php#ac-form-23
3. The page will show just the number 0 and nothing more

The user should press back button and then refresh the page to see the comment posted. In a very active network this is a big issue.

[DJPaul]

Duplicate of #4566