Time objects can break session

Error
Invalid serialization data for DateTime object
SYSTEMPATH/Session/Session.php at line 1005

Code:

998         if (ENVIRONMENT === 'testing')
999         {
1000             $_SESSION = [];
1001             return;
1002         }
1003
1004         // @codeCoverageIgnoreStart
1005         session_start();
1006         // @codeCoverageIgnoreEnd
1007     }
1008
1009     //--------------------------------------------------------------------
1010
1011     /**
1012      * Takes care of setting the cookie on the client side.

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Now this is puzzling. I found this fix:
https://github.com/codeigniter4/CodeIgni...78b1bdc1b3
But when I look at the current code on GitHub, Time::__wakeup() is not there. I added this function to my version of the Time class and so far it seems to be working fine.