EllisLab/CodeIgniter — pull request #2648 by richardkmiller (2013-09-18 18:20:14+00:00)
Title: Only send the session cookie once

From time to time we saw the Session library send the same ci_session cookie multiple times. It once sent it 6 times. Not sure why, but we wanted to reduce the duplication and make sure the header size didn't balloon unnecessarily.