Fixed at revision 27259.
Added code so that ace components ignore f:ajax behaviors.
The reason why there was no exception thrown on the server side, as I had expected, was because the f:ajax tag was being used without specifying an event, so the default event was being used for the ace component. However, the script rendered was being generated by the f:ajax class (javax.faces.component.behavior.AjaxBehavior) which assumes that the script will go in an on* attribute or in a context where the 'event' variable is defined, but in ace components we render the behavior scripts as part of a JSON object and we invoke those functions at different points of the code. So, the 'event' variable wasn't being found and an error was thrown. Now, the script from f:ajax won't be rendered, which will result in an empty function being called (unless there are other client behaviors like ace:ajax or ace:animation attached to the component).
Attached test case showing the error when using an ace:tooltip in a panel that uses the f:ajax tag.