TYPO3 Core

Steps to reproduce:

- Create a new Site Config with the languages "Default" (0) and "German" (1)
- Create a page A
- On page A, create a new textmedia element with a file reference.
- Translate page A and the textmedia element to german

- Now create a page B
- Translate page B to german
- Go to page A and copy the german localization of the textmedia element
- Go to page B and insert the textmedia element.
- Open up the newly copied textmedia element on page B and change the language of the element to "Default".

Internally, the textmedia tt_content elements sys_language_uid will now correctly. change from 1 to 0. But the file reference that belongs to this element will NOT be updated and still has the sys_language_uid 1.
We now have created a mess in the sys_file_reference table and all kind of weird bugs can now happen.
For instance, if you now go to the page module and try to translate all content element to "German" with the Translate button, the wizard will crash with an error 500 and the exception message:
"Child record was not processed". The tt_content textmedia element will not be translated, but the original tt_content (sys_language_uid) now has 3 file references instead of 1.