[TYPO3-mvc] Repository ->update with TYPO3 4.7.6 / 4.7.7

[Valentin Zickner]

Hi all,

I upgraded my TYPO3 site from TYPO3 4.7.5 to 4.7.6 (for 4.7.7 the same). 
After that, my ->update($object); on a repository failed.

In the server logfile the following message appears:
PHP Fatal error:  Call to a member function replaceObject() on a 
non-object in 
/var/www/typo3_src-4.7.6/typo3/sysext/extbase/Classes/Persistence/Repository.php 
on line 222
The "non-object" is $this->backend (and after that $this->session).

Looking in this file, I recognized, that the injection from the backend 
and session changed from:
$backend = $this->persistenceManager->getBackend();
$session = $this->persistenceManager->getSession();
to a global injection at the top of the file.

Why this do not work for me?

Regards,

Valentin