Image field's file translation doesn't work as expected

If you have a node with a image field, leave the image empty, then create a translated version and add an image to that, you'd expect the image field to stay empty in the original one. But it doesn't. The image you add to the translated version will be added to the original too.

If you add the image to the translated node and then go back to the original and delete the image, the original is without and image and the translated has the image. But if you edit the translated, the image gets added back to the original.

Steps to reproduce - did this in simplytest.me with RC4

1. Enable Language and Content translation
2. Add language (I added Finnish)
3. Add translation support for Article (which already has field_image per default installation). Make sure the "File" under "Image" is also checked.
4. Add article, keep it in English (default). Add a file for the image field or leave it empty.
5. Add a translation for the node, put a different image to the field_image
6. Go back to the original - it has the file you added to the translated one

Vanilla RC4 seems to be having problems with even the alt text - the same text goes for the both translations.