landing page: png preview not working

[ppanero]

After some investigation it boils down to the validation function of simple_image:

(Pdb) l
 18
 19
 20  	def validate(file):
 21  	    """Validate a simple image file."""
 22  	    max_file_size = current_app.config.get(
 23  ->	        "PREVIEWER_MAX_IMAGE_SIZE_BYTES", 0.5 * 1024 * 1024
 24  	    )
 25  	    return file.size <= max_file_size
 26
 27
 28  	def can_preview(file):
(Pdb) n
> /Users/ppanero/.virtualenvs/v5/lib/python3.7/site-packages/invenio_previewer/extensions/simple_image.py(25)validate()
-> return file.size <= max_file_size
(Pdb) max_file_size
524288.0
(Pdb) file.size
973107.0