Sortable: pass a fake event object to _mouseUp on cancel. Fixes #5882 - UI.Sortable .sortable( cancel ) call the this._mouseUp method without param.

(cherry picked from commit cf0c32f)

Author: scottgonzalez

ui/jquery.ui.sortable.js

@@ -360,7 +360,7 @@ $.widget("ui.sortable", $.ui.mouse, {
 
 		if(this.dragging) {
 
-			this._mouseUp();
+			this._mouseUp({ target: null });
 
 			if(this.options.helper == "original")
 				this.currentItem.css(this._storedCSS).removeClass("ui-sortable-helper");