Accordillon does not open when a header is clicked while accordion is animating

[Hypher]

Steps:

• make an accordion with at least 3 headers
• click two different closed headers quickly (less than 700ms between clicks)

What happens: Only the first one opens, the second is highlighted but not opened

What it should happen instead: The first header should collapse while the second opens

This is a real problem when a click event is bound to the header: the event is fired but the accordion does not display the right content.

Note: To emphasis the problem change jquery.ui.accordion.js:374 to a higher value than 700ms

[Scott González]

Duplicate of #3532.