Doctrine overwrites Book::$owner

Prerequisites

• Two entities in one-to-many relation (Author and Book in this example)
• This is where the bug manifests itself: The „many” side of the relation has a many-to-one relation to a yet another entity (Book::$owner to User)
• The aforementioned relation is eagerly loaded (src/User.php:21)
• Another, unrelated entity has a same many-to-one relation (Account::$user to User). As far as I understand the bug, this is only required, so we get a proxy of the entity instead of the entity itself.

Test scenario

• There is one of each entity in the database. The bug manifests itself during hydration
• We fetch the Book entity using a non-pk field (Book::$isbn)
• We fetch the Account (container) class to get the User entity as a proxy
• We assign the user entity to a previously empty User::$owner field
• We fetch the Author::$books collection, and hydrate it (toArray())

Expected behaviour

• Book::$owner field is set to the previously used User proxy class

Actual behaviour

• Book::$owner is empty

The field is overwritten in: vendor/doctrine/orm/lib/Doctrine/ORM/Internal/Hydration/ObjectHydrator.php:450