http://www.doctrine-project.org/jira/browse/DDC-3619
When using SoftDeleteable doctrine extension, an entity can be scheduled
for deletion, then persisted before flushing. In such a case, the entity
was removed from the unit of work identity map and no reference was
hold. This could lead to spl_object_hash collisions, and prevent
another, new entity to be persisted later.
This fix makes sure the unit of work identity map holds a reference to
the entity after it has been soft-deleted.
b492d61398