Applied the changes in the File: base_import/static/lib/select2/select2.js 

http://bazaar.launchpad.net/~ocb/ocb-addons/7.0/revision/9966

In the above link applied the reverse steps after that  cur is null issue fixed.

Example

The below code removed:-

/*  $(document).delegate("*", "mousemove", function (e) {
      $.data(document, "select2-lastpos", {x: e.pageX, y: e.pageY});
   }); */

The below code added:-

 this.dropdown.delegate(resultsSelector, "mousemove", function (e) {
   $.data(document, "select2-lastpos", {x: e.pageX, y: e.pageY});
  });