SP4: File usage in Fiel field: renaming does not automatically rewrite used file fields

I have a main content in one of my section with an image in the related image file field (a png file under a test directory under /shared.... so very classical... no accent).

This page is published. I renamed the file and click ok (with root). No warning (as this should be done transparantly). But when refreshing ym page both in live and edit, the image field is now empty!