Session and long polling

Hello,

I've just update my app from CI 2.2 to CI 3.0.6. By the way, thanks for keeping CI alive !
Everything work fine, except pages with long polling.
 
Here's how i test it : 

Load a page. Launch a long polling (xhr) for 30 seconds. Try to reload the page. The page will refresh only at the end of the long polling call. 

Log of the first load :

Code:

Loading Time: Base Classes   0.0171
Controller Execution Time 0.0469
Total Execution Time          0.0647

Log of the refresh :

Code:

Loading Time: Base Classes   0.0172
Controller Execution Time       29.0245
Total Execution Time          29.0424

The problem seems to be this request :

28.9773  SELECT GET_LOCK('bfa50f3e52f4ed5967e97e0fe5120bb7bfbc1da2', 300) AS ci_session_lock, where query time is always the long polling remaining time.

I use database sessions. It was working fine with CI 2.2.

Sorry for my english, hope you will understand my problem...

Regards