bug #19241 Fixed BC Layer in DoctrineChoiceLoader (Rootie)

This PR was merged into the 3.2-dev branch.

Discussion
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Fixed BC Layer in DoctrineChoiceLoader

| Q             | A
| ------------- | ---
| Branch?       | 3.1
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |

in the case when the BC Layer is used $idReader is not set to the right value.

Commits
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c44d71c Fixed BC Layer in DoctrineChoiceLoader

src/Symfony/Bridge/Doctrine/Form/ChoiceList/DoctrineChoiceLoader.php

@@ -75,6 +75,7 @@ class DoctrineChoiceLoader implements ChoiceLoaderInterface
             // form first to last argument as of 3.1
             $manager = $class;
             $class = $idReader;
+            $idReader = $objectLoader;
             $objectLoader = $factory;
         }