[BUGFIX] Children can not have another language as their parent

This is a patch solving the scenario described in comment #3
Might need a follow up to deal with the actual subject

Change-Id: I8c6c7e4c09500d6b9eb44f5224cdf8beb8e77a31
Resolves: #57988
Reviewed-on: https://review.typo3.org/29699
Reviewed-by: Jo Hasenau
Tested-by: Jo Hasenau