Non-translatabale image files in translatable image fields are editable when it is not allowed to be changed

Steps to reproduce:

1. Make a content type translatable, select "Hide non translatable fields on translation forms" and make the image file in a translatable field non-translatable:
2. Translate a node and try remove the image, and upload a new one.
3. Result: You get a form validation error "Non-translatable field elements can only be changed when updating the original language. "

But if the image can't be changed in the form, why is there a "Remove" button at the image field at all?

Suggested solution:
When "Hide non translatable fields on translation forms" is selected, make it not possible to remove/upload new non-translatable images in the translation form.