keep reference integrity on cascade persist

Total issues resolved: **1**

- [1074](doctrine#1074) [DDC-2996](http://www.doctrine-project.org/jira/browse/DDC-2996) [DDC-3160](http://www.doctrine-project.org/jira/browse/DDC-3160) [DDC-3208](http://www.doctrine-project.org/jira/browse/DDC-3208) Regression in change set state after `UnitOfWork::recomputeSingleEntityChangeSet()`

Tag 2.3.5

v2.4.0-RC2

Tag 2.4.0-RC1