Flagging translations as outdated in a pending revision causes multiple translations to be marked as affected

1. +++ b/core/modules/content_translation/src/ContentTranslationHandler.php
   @@ -256,6 +264,41 @@ public function retranslate(EntityInterface $entity, $langcode = NULL) {
   +      $metadata = $this->manager->getTranslationMetadata($revision_translation);
   +      if (!$metadata->isOutdated()) {
   +        /** @var \Drupal\Core\Entity\ContentEntityInterface $new_revision */
   +        $new_revision = $storage->createRevision($revision->getTranslation($langcode), $revision->wasDefaultRevision());
   +        $metadata = $this->manager->getTranslationMetadata($new_revision);
   +        $metadata->setOutdated(TRUE);
   +        $storage->save($new_revision);
   +      }
   

   Asked plach about this in slack. Feels like it ought somehow to be possible to mark a translation as outdated without having to create a new revision for each one - this would mean not marking the translations as affected though. Don't think we need to fix that in this issue buy maybe a follow-up to discuss.

2. +++ b/core/modules/content_translation/src/ContentTranslationManager.php
   @@ -158,8 +164,32 @@ protected function loadContentLanguageSettings($entity_type_id, $bundle) {
   +          $result = TRUE;
   

   Could we early return TRUE instead of the two breaks, and return FALSE at the end? Don't always like early returns, but given there's no logic based on $result it might be slightly more readable. I know this is a temporary function.

   Thought about moving this to content_moderation but since it's @internal and we don't want anyone calling it, putting it in content_moderation for content_translation to call doesn't seem great either.

I agree with the change in behavior, I don't believe I am qualified to review the implementation itself.

I committed #2949710: Pending revisions may become unavailable when untranslatable fields affect all translations. #9 has some duplicate hunks from that. Here's a reroll with those removed.

For #10, I just rebased. The actual work that's in the patch is not mine, but looks great to me. Therefore, RTBC, and removing credit from myself.

All right, let's plug this hole. Thanks for producing the fix so fast and for the discussions with @catch et al.

Still needs the followup opened.