EllisLab/CodeIgniter — pull request #1713 by samson-htw (2012-08-15 01:41:21+00:00)
Title: keep track of old session id to handle race condition

Handle session rotation race condition in a different way than the is_ajax_request check that is currently done. That check is still used as a fallback, but this way allows us to handle multiple requests to the server even if they are not ajax requests.

The major drawback is that it requires a new field to be added to the session table.

(same issue as https://github.com/EllisLab/CodeIgniter/pull/1283)