TYPO3 Core

Hi,
please apologize if any setting of this issue is wrong, it is my first one.

We did an typo3-update to 4.5.23 from 4.1.15, everything worked well instead of one custom extension which stored session data. Because of the big upgrade I expected some error in the extension but found nothing there. Further stepping into code reveals line 405 of class.tslib_feuserauth.php as the cause.
The whole if/else-statement will either clear the data or insert a new entry (if no timestamp was given), but when data got loaded from the database via fetchSessionData sessionDataTimestamp will be set, thus neither branch of the if/else is hit and no data stored.
Working order is restored by changing to 4.5.22.

So the regression is between 4.5.22 and 4.5.23, it is related to http://forge.typo3.org/issues/34964.
Typo3 4.5 was missing the update statement, which 4.6 did have:
Present (4.6): https://review.typo3.org/#/c/16955/2/typo3/sysext/cms/tslib/class.tslib_feuserauth.php
Missing (4.5): https://review.typo3.org/#/c/16956/2/typo3/sysext/cms/tslib/class.tslib_feuserauth.php

For the moment we downgraded 4.5.22, but just adding the update-branch should probably restore working state.