EllisLab/CodeIgniter — pull request #2750 by Liu-Kang (2013-12-02 13:27:56+00:00)
Title: Update Pagination.php line 420

I'm on PHP 5.4.14 array_merge throws error, line 420. $get variable is false if $_GET is empty and array_merge needs an array, just typecast it to array doesn't work, because it makes array(0 => 0). Anyways, this little hack does the job.