bf32125bad
This issue was introduced by a side-effect in 2.1.3 with d9f9228d95c5ab2a200b3e2d2b358c598267afb1. In this commit read-only objects where prevented to be updated. This lead to an invalid check not being performed in UnitOfWork#computeChangeSet which was present before where an association that was null would be injected into the originalEntityData using the UnitOfWork#setOriginalEntityProperty() method in the AbstractHydrator. This commit now explicitly sets this field to null using the same API so that is present during UnitOfWork#computeChangeSet.
Doctrine 2 ORM
Master: 
2.1.x: 
Doctrine 2 is an object-relational mapper (ORM) for PHP 5.3.2+ that provides transparent persistence for PHP objects. It sits on top of a powerful database abstraction layer (DBAL). One of its key features is the option to write database queries in a proprietary object oriented SQL dialect called Doctrine Query Language (DQL), inspired by Hibernates HQL. This provides developers with a powerful alternative to SQL that maintains flexibility without requiring unnecessary code duplication.