Fix embedded document parent before computing changeset

[alcaeus]

Fixes #1525.

The problem is that the changeset wrote down the old embedded document, which was then used when trying to persist changes. I don't like adding another check for the embedded document parent, maybe @malarzm has a better idea?

[malarzm]

The only thing that comes to my mind is removing the check in persist part of UoW and seeing if the new one will be sufficient for both cases (I think there was a test checking if the embedded document is changed as soon as persist is called but I think we could break that as we were mostly interested in having embedded document cloned eventually during flush, not in specific moment in time)

[alcaeus]

@malarzm tried that, with the following result:

1. Doctrine\ODM\MongoDB\Tests\Functional\EmbeddedTest::testReusedEmbeddedDocumentsAreClonedInFact
   Failed asserting that two variables don't reference the same object.

tests/Doctrine/ODM/MongoDB/Tests/Functional/EmbeddedTest.php:580

[malarzm]

That exact assertion could be removed as it was checking if embedded documents were cloned as soon as persist :)

[alcaeus]

@malarzm I removed the failing assertion, everything else works as expected.

[malarzm]

Cool!