unregister_widget not working in WordPress 3.8

[Dane Morgan]

Issue
The code

function remove_calendar_widget() {
    unregister_widget('WP_Widget_Calendar');
}

add_action( 'widgets_init', 'remove_calendar_widget' );

unregisters the calendar widget on a 3.7.1 install but does not unregister it on a 3.8 install on the same server

Steps
Add the above code to the functions.php file and open the widget management page in the dashboard.

Expected results
The calendar widget will not be available in the widgets list.

What I see instead
The calendar widget is still there in the list.

[Dane Morgan]

Actually, when i put that code into a plugin it does work, so maybe in 3.8 this function is no longer available to themes?

[SergeyBiryukov]

That snippet still works as expected for me in 3.8 when I put it into Twenty Fourteen's or Twenty Thirteen's functions.php file.

[Dane Morgan]

Okay, same here. So I am missing something else. This works as expected. Thank you.